


LIBRARY 


9 


UNIVERSITY  OF  CALIFORNIA. 

Received. j£^____4e  4&^2 >  18  . 

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QUADRUPL 


X 


BY 

WM.  MAVER,  JB.,  AND  MINOR  M.  DAVIS. 
» i  


WITH   CHAPTERS   ON 

The    Dynamo-Electric   Machine   in   Relation  to  the  Quadru- 
plex.     The  Practical  Working  of  the  Quadruplex. 
Telegraph   Repeaters,  and  the  Wheat- 
stone  Automatic  Telegraph. 


BY  WM.  MAVER,  JR. 


NEW  YORK: 
THE  W.  J.  JOHNSTON  CO.,  LIMITED, 

TIMES   BUILDING, 

1890. 


Copyright,  1884,  by  "W.  J.  JOHNSTON. 


PREFACE. 


WHEN  the  authors  of  the  following  description  of  the  Edison 
quadruplex  system  of  telegraphy  undertook  to  write  a  clear  and 
complete  explanation  of  that  system,  and  of  the  instruments  con- 
nected therewith,  they  felt  convinced  that  in  doing  so  they  would 
meet  with  encouragement  from  many  of  their  fellow  operators, 
especially  those  who  had  not  had  a  favorable  opportunity  to  study 
the  theory  or  to  investigate  the  practical  working  of  the  system. 

They  were  aware  that  among  the  employes  of  the  various  tele- 
graph companies  there  were  many  who  were  and  are  deterred  from 
gaining  a  closer  acquaintance;  with; the  more  complicated  systems  of 
telegraphy,  for  the  reason  that  the  text  books  are,  as  a  rule,  beyond 
their  comprehension,  and,  therefore,  the  information  they  are  in 
search  of  can  only  be  obtained  by  persistently  questioning  those 
who  are  better  informed  than  themselves,  a  method  requiring  much 
patience,  and  not  always  an  agreeable  one. 

To  meet  the  wants  of  this  class  was  their  principal  object,  and 
they  have  been  pleased  to  find  that,  judging  by  the  reception  which 
greeted  the  appearance  of  the  articles  in  the  pages  of  The  Operator, 
their  efforts  have  been  successful. 

In  the  following  description  of  the  quadruplex,  as  well  as  in  the 
other  articles  contained  in  this  book,  no  attempt  has  been  made 
to  display  erudition.  On  the  contrary,  it  has  been  the  aim  of  the 
writers,  if  they  erred  at  all,  to  err  on  the  side  of  simplicity. 

It  is  a  book  written  by  operators  for  operators,  and   numerous 


4  PREFA  CE. 

assurances  have  been  received,  that,  as  such,  it  has  been  useful. 
But  while  such  is  the  case,  they  also  hope,  and  have  reason  to  be- 
lieve, that  it  will  be  found  an  easy  source  of  information  to  those 
outside  of  the  telegraphic  fraternity,  who  may  desire  to  form  an 
acquaintance  with  these  various  systems  and  instruments. 

The  authors  take  this  opportunity  to  return  acknowledgments 
to  Mr.  C.  O.  Mailloux  for  valuable  hints  as  to  the  construction  of 
the  diagrams.  The  majority  of  the  diagrams  were  prepared  for 
the  engraver  by  the  same  gentleman. 

In  conclusion,  the  writers  hope  that  their  book  will  prove  to  be 
free  from  serious  blunders,  and  that  all  who  find  profit  in  reading 
what  is  herein  written  may  be  induced  thereby  to  seek  to  increase 
their  knowledge  of  electrical  matters  by  a  study  of  more  elaborate 
works  on  such  subjects. 


CONTENTS. 


PAGE 
The  Quadruplex. 

Chapter  1 — Development  of  the  Quadruplex, -  7 

"         2 — Introduction  and  Explanatory,  • 14 

«         3 — The  Transmitter,  Rheostat,  and  Condenser,      -     -     -  18 

"         4 — Stearns  Duplex, 25 

"         5 — Instruments  of  the  Polar  Duplex, 29 

«         6— The  Polar  Duplex,                                        35 

«         7_The  Quadruplex,                                                     ...  40 
«         g — The    Dynamo-Electric    Machine  in  relation  to  The 

Quadruplex, 55 

«         9— The  Practical  Working  of  The  Quadruplex,     -     -     -  73 

Telegraph  Repeaters,        .-- 86 

The  Wheatstone  Automatic  Telegraph,        ---• 110 


hfl 


THE  QUADRUPLEX. 


CHAPTER  I. 

DEVELOPMENT  OF  THE  QUADRUPLEX. 

In  1874,  Mr.  Thomas  A.  Edison  succeeded  in  getting  his  quadru- 
plex  into  such  shape  that  it  was  considered  fit  to  be  used  on  wires 
for  the  transaction  of  commercial  business. 

The  first  quadruplex  circuit  on  which  business  was  actually 
transmitted,  was  between  New  York  and  Boston.  At  this  time  the 
quadruplex  was  worked  on  what  is  known  as  the  bridge  system,  as 
seen  in  Fig.  1,  that  is,  the  receiving  instruments  were  placed  in  the 
arm  usually  allotted  to  the  galvanometer  in  the  Wheatstone  bridge, 
and  of  course  were  operated  by  the  excess  of  current  passing 
through  that  arm  precisely  as  a  galvanometer  would  be. 

At  this  time  the  instruments  were  not  wound  differentially. 

The  No.  2  relay  was  then,  as  now,  a  neutral  relay,  with  a  soft 
iron  armature,  but  with  an  ordinary  long  core. 

At  that  early  stage  of  the  history  of  the  quadruplex  system,  it 
cannot  be  said  that  it  was  a  complete  practical  success. 

The  principal  difficulty  appears  to  have  been  caused  by  the  un- 
steadiness of  No.  2  relay,  and  this  was  attributed  to  the  falling  back 
of  the  armature  of  the  No.  2  relay  at  the  moment  when  there  was 
no  battery  at  the  distant  end,  namely,  while  the  change  of  polarity 
was  taking  place  ;  but,  in  the  light  of  subsequent  experience,  it  may 
perhaps  be  questioned  whether  this  was  really  the  case. 

To  assist  in  obviating  this  trouble,  the  armature  lever  of  that  re- 
lay was  made  very  long,  and  at  its  other  end  it  was  furnished  with 
an  armature  placed  opposite  another  electro-magnet,  which  electro- 
magnet was  in  a  shunt  circuit  in  which  was  also  placed  a  condenser. 


8 


THE  QUADRITPLEX. 


This  condenser,  at  the  moment  of  change  of  polarity  at  distant  end, 
discharged  into  the  shunt  circuit,  and,  by  thus  magnetizing  the  extra 
electro-magnet,  held  the  lever  firmly  against  the  contact  point  for 
the  desired  time. 

In  1875  a  change  was  made  in  the  foregoing  arrangement,  the 
same  principles  being  retained,  but  the  differential  method  was 
adopted  and  both  Nos.  1  and  2  relays  were  polarized. 

The  armature  of  the  No.  2  relay  of  course  responded  to  all  changes 
of  polarity,  but  its  contact  points  were  so  arranged  that  when  the 
full  strength  of  current  was  to  the  line,  the  retractile  springs  were 
overcome  and  the  local  circuit  broken  as  seen  at  R 2,  Fig.  2. 


Fig-  2. 

The  next  alteration,  shown  in  Fig.  3,  consisted  of  a  novel  arrange- 
ment of  the  circuit,  which  did  not  require  the  polarity  to  be  reversed 
during  the  transmission  of  a  signal.  The  diagram  shows  the  con- 


THE  QUADRUPLEX.  9 

nections  necessary  for  working  this  device  on  the  diplex  system, 
that  is,  for  sending  two  messages  in  the  same  direction  simulta- 
neously. By  the  adoption  of  any  of  the  duplex  systems,  this  method 
can  be  converted  into  the  quadruplex  system.  Mr.  Gerritt  Smith 
was  the  inventor  of  this  ingenious  arrangement. 


Fig  3. 

Following  this  came  a  supposed  improvement  of  the  original 
arrangements  of  the  quadruples  (Fig.  4),  which,  as  may  be  seen,  is  a 
combination  of  the  bridge  and  differential  methods.  The  No.  1  relay 
was  placed  in  the  bridge,  and  the  No.  2  relay  (now  transformed 
into  a  compound  polarized  relay,  also  an  invention  of  Mr.  Gerritt 
Smith,)  was  placed  in  the  line  and  the  rheostat  wires,  as  at  present. 


10 

As  in  the  former  case  the  No.  2  relay,  Sr  in  the  figure,  responded 
to  either  polarity,  but  only  broke  the  local  circuit  when  full  battery 
was  to  the  line  at  distant  end.  Subsequently  both  relays  were 
again  placed  differentially,  a  polarized  relay,  for  increase  and  de- 
crease of  strength,  still  being  retained.  (Fig.  5.) 


LIN  t 


GROUND 


Fig.  4. 

About  this  time  a  condenser  was  placed  between  the  two  relays, 
one  series  of  its  plates  being  connected  to  the  rheostat  wire,  the 
other  series  to  the  line  wire,  which  was  found  to  be  of  service. 
This  arrangement  was  devised  by  Mr.  F.  W.  Jones,  at  that  time  in 
Chicago. 

About  this  time  also  a  combination  relay,  shown  in  Fig.  6,  capable 
of  performing  the  service  of  the  present  No.  1  and  No.  2  relays  was 


THE  qiTADRUPLEX. 


11 


introduced.  It  may  be  seen  by  following  out  the  local  connections 
that  the  armature  will  give  the  correct  signal  for  increase  and  de- 
crease of  strength,  regardless  of  the  side  on  which  it  may  be  giving 
a  polarity  signal.  This  device  worked  successfully,  but  it  was  found 


Fig.  5. 

more  desirable  to  have  two  separate  relays  so  that  each  receiving 
operator  could  have  control  of  the  adjustment  of  his  own  instru- 
ment. 

Fig.  7  shows  the  stage  at  which  the  system  had  arrived  in  1878, 
four  years  after  its  first  appearance. 

At  that  time  the  compound  polarized  relay  was  still  used  as  the 


12 


THE  QUADRUPLEX. 


No.  2  relay.  The  local  contact  points,  as  heretofore,  were  so 
arranged  as  to  close  the  local  circuit  only  when  full  battery  at  dis- 
tant end  was  to  the  line. 

Then  followed  the  introduction  of  the  short  core  No.  2  relay,  upon 
the  advent  of  which  a  marked  improvement  in  the  working  of  the 
system  was  discernible,  and  not  only  in  the  working  of  the  system, 
but  in  the  facility  with  which  the  No.  2  relay  could  be  adjusted. 

c 


Since  that  time  no  further  improvements  have  been  added  to  the 
system.  Indeed,  it  is  difficult  to  imagine  in  what  respects  it  could 
now  be  improved.  In  fair  weather  and  under  good  conditions  as 
regards  management,  etc.,  the  system  approaches  very  near  perfec- 
tion. 

The  continuity  preserving  transmitter  has  retained  its  original 
shape  throughout,  but  the  pole  changer  has  seen  about  as  many 
changes  in  the  form  of  its  construction  as  there  have  been  methods 


THE  QUADRUPLEX. 


13 


employed  in  the  endeavor  to  bring  the  quadruplex  system  to   its 
present  shape. 


We  are  mainly  indebted  to  Prescott's  description  of  the  quadru- 
plex for  the  foregoing  information. 


II. 


INTRODUCTORY  AND  EXPLANATORY. 

It  is  purposed  in  these  articles  to  present  a  description  of  the 
Edison  or  Western  Union  standard  quadruplex  in  such  a  manner 
as  will  be  easily  understood  by  every  one.  It  is  not  expected  that 
the  explanation  can  be  made  so  plain  that  it  will  be  understood 
without  study  on  the  part  of  the  reader  ;  but  it  is  hoped  that  the 
amount  of  application  necessary  will  be  reduced  to  a  minimum  by 
the  use  of  simple  terms  and  lucid  illustrations. 

This  quadruplex  is,  with  some  slight  changes,  virtually  a  combi- 
nation of  the  Stearns  and  polar  duplexes.  If,  therefore,  we  ac- 


Fig.  8. 

quire  a  distinct  knowledge  of  the  theories  of  these  duplexes,  it  will 
be  comparatively  an  easy  task  to  comprehend  the  manner  of  their 
combination  in  the  quadruplex. 

The  instruments  used  in  the  working  of  these  duplexes  are 
similar  to  those  required  in  the  quadruplex,  namely,  the  single-cur- 
rent transmitter  and  neutral  relay  of  the  Stearns  system,  and  the 
pole  changer  and  polarized  relay  of  the  polar. 

The  function  of  the  single-current  transmitter  is  to  increase  and 


THE  QUADRUPLEX. 


15 


decrease  the  strength  of  current  on  the  line :  that  of  the  pole 
changer  is  to  change  the  direction  of  the  current. 

The  office  of  the  neutral  relay  is  to  respond  to  the  increase  or 
decrease  of  current  on  the  line,  while  that  of  the  polarized  relay  is 
to  respond  to  the  changes  of  polarity  of  the  current.  Both  relays 
are  wound  differentially,  as  will  be  explained. 

Here  are  two  distinct  principles  which,  when  properly  combined, 
give  us  the  quadruplex. 

We  will  proceed  to  inspect  the  manner  of  working  the  Stearns  du- 
plex, but,  before  doing  so,  it  will  be  necessary  to  examine  some  of 
the  laws  of  electricity  and  magnetism  on  which  its  operation  is  based. 


Fig.  9. 


If  electricity  be  passed  through  a  coil  of  wire  encircling  a  bar  of 
soft  iron,  the  bar  will  become  a  magnet,  the  polarity  of  which  will 
be  determined  by  the  direction  in  which  the  current  passes  around 
the  bar.  The  iron  will,  however,  lose  its  magnetism  the  moment 
the  current  ceases.  If  the  wire  be  wound  around  the  bar,  as  shown 
in  Fig.  8,  and  if  the  current  be  passing  in  the  direction  indicated 
by  the  arrow  S,  the  poles  will  be  as  indicated  in  the  figure. 

Winding  the  wire  in  the  opposite  direction  around  the  bar, 
the  current  retaining  the  same  direction,  reverses  the  polarity  of 
the  magnet,  as  shown  in  Fig.  9. 

It  follows  that  if  two  equal  currents  are  caused  to  pass  around 
the  bar  in  opposite  directions,  tending  to  establish  exactly  opposite 


16 


THE  QITADRUPLEX. 


effects,  they  will  neutralize  each  other,  and  the  bar  will  remain  non- 
magnetic. 

If  we  bend  the  bar  to  the  form  of  a  letter  U,  both  poles  of  the 
magnet  will  exert  whatever  attractive  force  is  developed,  upon  an 
unmagnetized  cross  piece,  or  armature,  as  may*  be  seen  in  ordinary 
relay  and  sounder  magnet. 

If  we  connect  one  pole  of  a  battery  with  the  earth  and  from  the 
other  pole  run  to  the  earth  two  wires  of  equal  resistance  (Fig.  10), 
equal  currents  will  traverse  the  wires. 


Fig.  10. 

These  principles  are  employed  in  the  Stearns  differential  system 
in  the  following  manner :  Suppose  a  wire  A  (Fig.  11)  is  led  from 
a  battery  around  a  bar  of  soft  iron  from  left  to  right,  over  the  bar, 
and  another  wire  of  equal  resistance  B  around  from  right  to  left, 
two  equal  opposing  actions  will  be  set  up  in  the  bar,  one  exactly 
offsetting  the  other,  and  no  magnetic  effect  will  be  produced.  A 
relay  thus  wound  is  called  a  differential  relay. 


THE  QUADRUPLEX. 


17 


Now,  suppose  a  battery  is  introduced  at  the  distant  end  of  B 
(Fig.  12),  and  note  the  result. 

Battery   C  supplies  each  wire  with  an  equal  current,  having  a 

strength  of,  say,  2.     Battery  D  adds  to  the  strength  of  the  current 

traversing  wire  B  an  additional  strength  of  2,  making  a  strength  of 

4  upon  wire  J5,  a  surplus  of  2  above  that  on  A,  which  is  sufficient 

B 


Fig.  12. 

to  neutralize  the  magnetism  which  the  current  in  wire  A  would 
tend  to  set  up,  and  to  establish,  by  means  of  its  excess  of  strength, 
a  magnet,  the  polarity  of  which  is  determined,  as  in  the  previous 
cases,  by  the  direction  of  the  current  around  the  bar. 

Let  us  take  an  illustration  frequently  used.     Suppose  a  wheel 
(Fig.  13)  upon  the  opposite  sides  of  which  two  streams  of  water 


Fig.  13. 

are  falling  with  equal  force.  So  long  as  these  forces  continue  equal 
the  wheel  does  not  move,  but  upon  increasing  the  pressure  on  one 
side,  the  force  acting  upon  the  other  will  be  overcome,  and  the 
wheel  will  revolve.  In  a  similar  manner  the  excess  of  electrical 
force  in  one  of  the  coils  overcomes  the  opposing  force  in  the  other. 


CHARTKR   III. 
THE  TRANSMITTER,  RHEOSTAT  AND  CONDENSER. 

In  order  to  produce  rapidly  and  conveniently  the  magnetic  effect 
described,  instruments  specially  adapted  to  the  work  are  used. 
Let  us  first  examine  the  transmitter. 

THE  TRANSMITTER. 

In  the  Stearns  duplex,  the  office  of  the  transmitter,  or  continuity 
preserving  key,  is  to  alternately  place  the  battery  and  the  earth  in 
contact  with  the  line,  substituting  one  the  instant  the  other  is  re- 
moved ;  thus  preserving,  with  the  exception  of  a  slight  interval 
noted  further  on,  a  continuous  circuit  at  all  times. 

A  (Fig.  14)  is  an  electro-magnet  controlling,  by  means  of  local 
battery  L  B  and  key  K,  the  action  of  armature  lever  B.  0  is  a  thin 
tongue  of  elastic  metal  attached  to  the  lever  5,  but  insulated  from  it. 
The  lever  B  is  bent  at  one  end,  as  shown,  and  the  tongue  extends 
just  below  the  arm  of  the  bend  in  such  a  position  as  to  come  in  con- 
tact with  it  at  the  point  X.  The  post  D  is  insulated  from  the  base 
upon  which  it  stands,  and  supports  the  screw  6r.  This  screw  is  so 
adjusted  as  to  intercept  the  upward  movement  of  the  tongue  when 
the  transmitter  is  closed,  establishing  contact  at  E  and  breaking  it 
at  X.  Now,  if  the  battery  be  connected  to  D,  the  ground  to  j5,  and 
the  line  to  the  tongue  C",  the  instant  we  close  the  transmitter,  screw 
Cr  places  the  battery  in  contact  with  the  line  at  E,  while  it  pushes 
the  tongue  downward  at  JT,  breaking  contact  at  that  point.  The 
screw  S  regulates  the  play  of  the  armature  lever.  The  relay  used 
in  the  Stearns  duplex  is  differentially  wound,  but  is  otherwise  con- 
structed like  those  in  ordinary  use. 


THE  QITADRUPLEX. 
THE  RHEOSTAT. 


19 


In  the  systems  of  duplexes  and  quadruplex  which  we  are 
studying,  we  have  two  wires  wound  around  the  cores  of  electro- 
magnets in  opposite  directions,  so  that  the  currents  from  the  home 
battery  have  no  effect  upon  the  cores,  as  one  current  neutralizes  the 
other ;  in  other  words,  one  wire  balances  the  other. 

By  placing  another  battery  at  the  distant  end  of  one  of  these 
wires,  however,  we  have  seen  that  we  can  diminish  or  increase  the 


Line 


|crouiui[  [flrouii(t| 

Fig.  14. — THE  TRANSMITTER. 

strength  of  the  current  passing  through  that  wire  so  that  the  equi- 
librium which  the  home  battery  tends  to  maintain  in  the  cores  is 
overcome,  and  we  can  thus  operate  tlie  home  electro-magnets  from 
the  distant  end,  at  will.  Now,  as  the  object  of  the  multiplex  sys- 
tems is  to  double  or  quadruple  the  capacity  of  the  existing  wires 
between  any  two  places,  it  is  evident  that  one  of  the  wires  which 
we  use  to  preserve  the  equilibrium  in  the  electro-magnets  must  be 
comparatively  of  no  expense,  or  nothing  will  be  gained.  For  in- 
stance, if  we  desired  to  set  up  a  duplex  between  any  two  points, 


20  THE  QUADRITPLEX. 

and  were  to  use  two  of  the  wires  already  running  to  those  points, 
one  wire  to  balance  the  other,  it  is  manifest  that,  although  we 
should  literally  make  one  wire  do  the  work  of  two,  we  should  act- 
ually still  be  using  two  wires  to  accomplish  the  feat. 

It  is  a  law  of  electricity  that  with  a  given  electro-motive  force  the 
strength  of  current  will  depend  on  the  resistance  of  the  conductors 
through  which  the  electricity  is  required  to  pass. 

It  is  not  necessary  that  the  two  wires  should  be  of  the  same 
length,  size,  or  material.  Provided  the  resistance  of  the  conductors 
is  the  same,  the  strength  of  current  will  be  equal  in  each.  Certain 
metals  offer  a  much  less  resistance  to  electricity  than  others.  Thus 
the  capacity  of  iron  wire  as  a  conductor  is  more  than  twice  that  of 
German  silver.  This  is  supposing  the  metals  to  be  of  equal  thick- 
ness. The  thicker  we  make  a  metal,  the  more  we  increase  its 
capacity  as  a  conductor.  Conversely,  the  thinner  we  make  a  metal 
the  poorer  a  conductor  it  becomes ;  in  other  words,  its  resistance  is 
greater.  So  it  is  possible,  by  using  iron  of  a  certain  thickness  for 
one  of  the  wires  under  consideration,  and  for  the  other  a  very  much 
thinner  German  silver  wire,  to  make,  say,  500  miles  of  iron  wire 
equal  in  point  of  resistance  to  perhaps  but  half  a  mile  of  German 
silver  wire,  and  a  given  battery  will  produce  as  great  a  strength  of 
current  in  the  iron  wire  as  in  the  much  shorter  German  silver  wire. 
This  fact,  then,  is  taken  advantage  of  in  these  multiplex  systems, 
and  an  artificial  wire  consisting  of  coils  of  fine  German  silver  con- 
tained in  a  box  termed  a  rheostat  is  used  as  a  balancing  wire. 

Fig.  15  shows  the  manner  in  which  the  coils  are  connected  to  the 
brass  discs  on  the  cover  of  the  box  and  to  each  other.  A  brass 
plug  inserted  between  any  two  of  the  discs  virtually  cuts  out  one 
of  the  coils,  as  it  provides  a  route  of  practically  no  resistance  for 
the  current.  The  coils  are  wound  double  upon  themselves,  as 
shown  in  the  figure,  which  prevents  any  inductive  effects,  the  law 
of  electricity  bearing  on  this  point  being  "  that  a  circuit  doubled 
back  upon  itself  so  that  the  current  flows  back  along  a  path  close 
to  itself  exerts  no  force  upon  external  points.'* 

Thus  we  have  a  simple  means  of  obtaining  a  wire  which  we  can 


THE  QUADEUPLEX. 


21 


adjust  to  correspond  with  a  line  wire  of  almost  any  resistance.  If, 
for  example,  we  have  a  wire,  as  in  the  figure,  3,000  ohms  resist- 
ance, we  simply  unplug  as  many  coils  in  the  rheostat  as  may  be 
necessary  to  bring  the  artificial  wire  up  to  the  same  resistance,  and 
if  by  reason  of  wet  weather  the  resistance  of  the  line  wire  de- 
creases, we  reduce  the  resistance  of  the  rheostat  by  inserting  more 
plugs  between  the  discs ;  for,  if  we  do  not  preserve  the  balance  be- 


400  300   200 


Fig.  15. 

tween  the  two  wires,  the  home  battery  will  operate  the  home  relays 
and  thus  interfere  with  the  signals  from  the  distant  end.  The  fig- 
ures on  the  brass  discs  represent  the  amount  of  the  resistance  in 
ohms  of  the  coils  attached  to  them. 

THE  CONDENSER. 

As  without  the  use  of  condensers  or  some  other  instrument  capa- 
ble of  performing  a  similar  service,  it  would  be  impossible,  for  rea- 
sons which  will  be  explained  hereafter,  to  successfully  work  the 
multiplex  systems  on  lines  of  any  great  length,  it  will  be  proper  to 
devote  some  space  to  a  description  of  their  action  and  manner  of 
construction : 

It  is  a  well  known  law  of  both  electricity  and  magnetism  that  like 
poles  repel  and  unlike  poles  attract  each  other. 


22 


THE  QITADRUPLEX. 


If  by  any  means  we  electrify  any  insulated  conductor  with  elec- 
tricity of  one  polarity,  that  electricity  will  tend  to  attract  toward 
itself  in  surrounding  objects  sufficient  electricity  of  opposite  polarity 
to  establish  equilibrium,  or  what  is  termed  a  non-electric  state. 


Fig.  16. 

Electricity  thus  attracted  in  surrounding  conducting  objects  is 
called  induced  electricity,  and  this  property  of  inducing  electricity 
in  other  objects  is  termed  induction.  All  substances  are  not 
equally  susceptible  to  inductive  influence.  Good  conductors  of 
electricity  generally  are,  while  insulators  are  not.  In  Fig.  16,  A 
and  B  are  supposed  to  be  insulated  metal  spheres  remote  from  other 
conducting  bodies.  If  A  be  charged  with  positive  electricity  from 
an  electrical  machine,  it  will  at  once  receive  all  the  electricity  which 
it  will  apparently  hold.  If  B  be  now  brought  close  to  A,  it  will  be 
found  that  A  will  receive  more  electricity,  because  the  positive 
electricity  on  A  has  attracted  a  corresponding  quantity  of  negative 
electricity  on  the  side  of  B  nearest  A,  and  has  repelled  an  equal 
amount  of  positive  electricity  to  the  opposite  side  of  J9,  and  in  the 


THE  QUADRUPLED. 


23 


effort  of  the  two  polarities  to  unite  they  have  become  gathered  or 
condensed  upon  the  sides  of  the  spheres  nearest  each  other.  If  we 
now  connect  B  with  the  earth,  thus  allowing  the  positive  electricity 
on  B  to  escape,  it  will  be  found  that  A  will  receive  a  still  further 
charge  of  positive  electricity,  and  B  will  take  up  a  corresponding 
amount  of  negative  electricity.  So  long  as  A  is  kept  electrically 
charged,  the  electricity  which  has  been  induced  in  B  will  be  held 

Lino 


Condenser 


Fig.  17. 

in  .B,  but  the  instant  we  provide  a  conductor  to  the  earth  for  A,  the 
induced  electricity  in  B  will  simultaneously  flow  to  the  earth. 

We  cannot  interpose  any  known  substance  between  the  spheres 
which  will  prevent  the  above  described  inductive  action  from  tak- 
ing place.  The  least  inductive  effect  is  produced  when  the  plates 
are  separated  merely  by  air ;  the  greatest  when  they  are  separated 
or  insulated  by  mica.  The  closer  the  plates  can  be  brought  with- 
out touching,  the  greater  the  inductive  effects  will  be. 


24 


THE  QUADRUPLEX. 


Condensers  are  constructed  in  accordance  with  the  foregoing 
laws.  They  are,  therefore,  generally  composed  of  sheets  of  tin-foil 
connected  alternately  to  a  battery  wire  and  to  the  earth,  as  seen  in 
Fig.  17.  Each  sheet  is  separated  from  the  other  by  some  insulating 
substance,  preferably  mica,  on  account  of  its  thinness  and  high  in- 
ductive capacity,  although  paraffine  paper  is  frequently  used.  Sup- 
posing the  lines  in  Fig.  17  to  represent  the  foil,  and  the  spaces  the 
insulating  material,  the  plan  of  a  condenser  will  be  understood. 
The  current  passing  to  the  line  charges  one  set  of  plates  as  shown, 
which  induces  electricity  of  an  opposite  polarity  in  the  ground 
plates,  and  this  in  turn  condenses  electricity  in  the  line  plates,  ac- 
cumulating therein  a  charge  in  proportion  to  the  number  of  plates 
in  action. 


? 

4 

CT 

3     2 
8 

D  "q 

f6 

3      l± 
32 

3 

to 

Fig.  18. 

In  Fig.  18  the  general  plan  of  the  condenser  is  shown.  All  the 
lower  plates  are  connected  with  the  thumb-screw  B,  which  can  be 
readily  connected  with  the  earth,  and  the  upper  plates  to  J.,  to 
which  the  line  can  be  attached.  By  inserting  plugs  at  a  a  a  a  a, 
more  plates  may  be  connected,  and  thus  the  amount  of  charge  in- 
creased as  desired. 


CHAPTKR   IV. 

THE  STEARNS  DUPLEX. 

Fig.  19  is  a  diagram  showing  the  theoretical  arrangements  neces- 
sary to  the  working  of  this  duplex  system. 

In  it  T  and  T'  are  transmitters  worked  by  means  of  a  local  battery 
and  key.  R  and  R'  are  relays  differentially  wound.  E  and  E'  are 
resistance  coils,  or  rheostats,  which  furnish  a  method  of  making  an 
artificial  resistance  equal  to  that  of  the  line.  ^Tand  H'  are  condens- 
ers, the  manner  of  use  of  which  will  be  explained  later  on. 

Having  made  the  rheostat  resistance  equal  to  the  line  resistance, 
we  have  at  each  end  the  conditions  described  in  Fig.  12;  the  line 
wire  representing  wire  B  of  that  figure  and  the  rheostat  wire  A,  the 
core  of  each  relay  being  equivalent  to  our  soft  iron  bar. 

Now  let  us  see  what  takes  place.  Suppose  T  to  be  closed,  and 
T'  open.  (In  the  diagram  both  transmitters  are  represented  as 
closed.)  In  this  position  of  the  transmitters  it  is  seen  that  battery 
F  is  in  contact  with  the  line,  while  battery  I"  will  be  cut  off  at  6r'. 

Thus  equal  currents  from  battery  F  will  pass  in  opposite  direc- 
tions around  the  cores  of  relay  72,  one  portion  going  to  the  ground 
through  coil  A  of  relay  R,  and  the  rheostat ;  the  other,  via  the  line 
and  through  coil  B'  of  relay  R'  to  the  ground  at  Q'.  Thus  battery 
F  produces  no  effect  on  relay  R,  but  in  traversing  coil  B'  of  R'  it 
magnetizes  the  core  of  the  latter,  and  its  armature  is  attracted,  re- 
cording a  signal.  Let  us  say  that  the  current  from  battery  F  in 
passing  through  coil  B'  of  R'  produces  a  magnetic  strength  of  2 
in  the  core  of  the  latter.  Let  us  also  grant,  for  the  sake  of  illustra- 
tion, that  it  is  passing  through  coils  A  and  B  of  relay  R  with  a 
strength  of  2  each — but  owing  to  the  fact  that  this  strength  is 
exerted  in  opposite  directions  no  effect  is  perceptible — and  let  this 


26 


THE  Q  UADR  UPLEX. 


THE  QUADRUPLEX.  27 

also  be  true  of  the  effect  of  battery  F'  on  the  cores  of  relay  R\ 
when  F'  is  placed  in  the  circuit,  viz.,  that  it  has  a  strength  of  2. 

Should  transmitter  T'  be  now  closed,  as  in  the  figure,  breaking 
circuit  at  x',  and  placing  battery  F'  in  the  circuit,  wire  a'  of  relay 
Rf  will  now  carry  a  current  of  a  strength  of  2,  but  an  additional 
strength  of  2  has  been  given  to  the  current  traversing  wire  B1. 
Wire  B'  of  relay  R'  therefore  still  carries  a  greater  current  than 
wire  A'  of  the  same  relay,  viz.,  as  4  to  2,  consequently  that  relay  re- 
mains closed,  while  the  current  in  wire  B  of  relay  R  is  also  in- 
creased by  the  current  of  2  from  battery  .F',  and  is  now  of  greater 
strength  than  that  upon  wire  A  of  that  relay,  hence  magnetism  is 
produced  in  its  core,  and  the  armature  is  attracted,  both  relays  be- 
ing now  closed.  If  transmitter  T  be  now  opened,  it  will  be  seen 
that  the  current  from  battery  F  is  removed  from  the  line,  and  the 
currents  in  wires  A'  and  B'  of  relay  R'  become  equal,  consequently 
the  core  of  that  relay  loses  its  magnetism,  and  the  armature  is 
pulled  back  by  the  retractile  spring,  opening  the  local  circuit ;  but, 
as  there  is  still  a  current  in  coil  B  of  relay  R,  and  none  in  coil  A, 
that  relay  remains  closed.  Thus  it  is  seen  that  under  all  circum- 
stances battery  F  produces  an  active  effect  only  on  relay  R',  and 
that  battery  F'  only  operates  relay  R,  and  hence  two  messages  may 
simultaneously  be  sent  in  opposite  directions. 

A  line  wire  acts  to  a  certain  extent  like  a  condenser.  When  it 
is  connected  with  a  battery  it  becomes  charged,  and  whenever  the 
proper  conditions  exist  along  its  route  it  will  induce  electricity  in 
adjoining  conducting  objects,  and  thus  is  enabled  to  take  up  a 
greater  charge.  In  this  duplex  system,  when  we  open  the  trans- 
mitter, and  thus  suddenly  cut  off  the  battery,  and  substitute  a  path 
to  the  earth,  a  portion  of  the  charge  will  come  back,  and  pass  to 
the  earth  by  this  route  rather  than  overcome  the  greater  resistance 
to  the  distant  end. 

This  discharge  varies  in  quantity  with  the  strength  of  the  charg- 
ing battery  and  the  length  and  size  of  the  wire.  Thus  there  are 
many  short  duplex  and  quadruplex  circuits  on  which  this  line  dis- 
charge, or  static  discharge,  as  it  is  often  called,  is  so  small  or  dis- 


28  THE  QITADRUPLEX. 

charges  itself  so  quickly  that  no  effect  is  produced  on  the  instru- 
ment. But  on  long  circuits  it  becomes  so  great  that  in  passing 
through  the  line  coil  of  the  relay  a  momentary  magnetization  of  the 
core  is  caused,  which  attracts  the  armature  and  makes  a  false  sig- 
nal. In  order  to  counteract  this  effect,  a  condenser,  which  can  be 
adjusted  to  equal  the  accumulative  capacity  of  the  line  wire,  is  con- 
nected to  the  rheostat  coil  of  the  relay  (as  seen  in  the  diagram)  so 
that  its  discharge  may  traverse  that  coil  in  an  opposite  direction 
around  the  core,  and  at  the  same  instant  that  the  line  discharge  trav- 
erses the  line  coil,  thus  neutralizing  the  effect  of  that  discharge. 
Further  allusion  will  be  made  to  the  action  of  the  condenser  when 
we  consider  the  quadruplex. 

The  elements  of  batteries,  that  is,  the  zinc,  copper  and  liquids, 
offer  resistance  to  the  passage  of  the  current  through  them ;  this  is 
called  "internal  resistance."  In  order  to  keep  the  resistance  the 
same  whether  the  circuit  is  completed  through  the  battery,  or 
through  the  armature  lever  of  the  transmitter,  to  the  earth,  resist- 
ance coils  Q  and  Q'  (Fig.  19),  having  a  resistance  equal  to  the  in- 
ternal resistance  of  the  home  battery,  are  inserted  between  the 
levers  of  the  transmitters  and  the  earth. 


V. 


INSTRUMENTS  OF  THE  POLAR  DUPLEX. 

THE  POLE  CHANGER. 

Figure  20  presents  an  end  view  of  a  pole  changer,  with  its  the- 
oretic battery  connections. 

The  square  B  represents  one  end  of  the  armature  lever,  which 
protrudes  through  a  hole  in  the  center  of  the  disc  K.  The  squares 
on  either  side  are  screwed  to  the  metallic  disc  JT,  but  the  tongues 
T  and  T',  each  having  two  contact  points,  while  supported  by  the 


linn 


Fig.  20. 

disc  JT,  are  insulated  from  it.  Each  tongue  is  connected  to  a  pole 
of  the  battery.  The  bar  B,  or  armature  lever,  is  connected  to  earth. 
The  line  wire  is  connected  to  the  disc  K.  In  the  figure,  the  key 
of  local  circuit  controlling  the  pole  changer  is  presumed  to  be 


30 


THE  QVADRVPLEX. 


closed,  hence  the  lever  B  has  made  contact  with  the  upper  tongue 
T,  raising  it  from  the  square  S  on  the  left  hand  side,  and  has  at  the 
same  time  released  the  lower  tongue  which  has  risen  by  its  own 
tension  and  made  contact  with  the  square  on  right  hand  side.  The 
circuit  is  thus  complete,  from  the  earth  at  E,  through  lever,  to  the 
upper  tongue  T,  to  the  negative  pole  of  the  battery,  through  bat- 
tery to  the  lower  tongue  T',  thence  to  the  line.  Thus  in  this  case 
the  positive  pole  of  battery  is  to  the  line,  and  the  direction  of  the 
current  is  shown  by  the  arrows. 


Fig.  21. 


Fig.  21  shows  the  pole  changer  with  key  open.  The  lever  B  has 
now  made  contact  with  the  lower  tongue  T',  detaching  it  from  the 
right  hand  square  S.  It  has  at  the  same  time  released  the  upper 
tongue  T,  which  now  descends  and  connects  with  the  left  hand 
square  S.  The  circuit  is  again  complete,  from  the  line  to  square  S, 
to  tongue  T,  to  negative  pole  of  battery,  through  battery  to  lower 
tongue  T'  and  earth,  and  the  direction  of  current  is  now  changed 
as  shown  ^»y  arrows.  Thus  at  each  motion  of  the  lever,  up  or 
down,  the  poles  are  changed  and,  consequently,  the  direction  of 
the  current. 


THE  QUADRUPLEX. 


31 


In  Figs.  8  and  9  we  have  seen  that  according  to  the  direction 
of  the  current  around  the  bar  is  determined  the  magnetic  polarity 
of  the  bar.  In  those  cases  the  direction  of  the  current  around  the 
bar  has  been  changed  by  winding  the  coils  in  opposite  directions, 
so  that  the  current  has  been  made  to  go  around  the  bars  in  differ- 
ent ways.  We  might  have  obtained  the  same  results  by  changing 
the  direction  of  the  current  on  the  wire  and  leaving  the  coil  wound 
in  one  way.  If  we  know  the  direction  in  which  a  current  is  trav- 
ersing a  bar,  we  can  tell  the  position  of  the  magnetic  poles  of  the 
bar  by  the  following  rule :  Suppose  that  we  are  looking  at  one 


Fig.  22. 

end  of  the  bar ;  if  the  current  is  circulating  around  the  bar  (with 
relation  to  the  position  in  which  we  are  looking  at  it)  in  the  direc- 
tion in  which  the  hands  of  a  clock  move,  then  the  end  at  which  we 
are  looking  is  a  south  pole,  and  vice  versa. 

When  a  positive  pole  of  a  battery  is  placed  to  a  line  wire,  the 
current  is  supposed  to  flow  out  on  the  line ;  when  a  negative  pole 
of  a  battery  is  to  the  line,  the  current  is  supposed  to  flow  in  from 
the  line.  If  the  reader  who  is  beginring  the  study  of  the  polar  du- 
plex will  bear  this  in  mind,  it  will  simplify  the  study  considerably, 


32 


THE  QUADRUPLEX. 


and  it  will  be  well  to  remember  that  when  we  have,  say,  50  positive 
cells  of  battery  at  one  end  of  the  wire  and  50  cells  of  positive  bat- 
tery to  the  line  at  the  other  end,  there  will  be  no  flow  of  current  on 
the  line,  as  these  batteries  neutralize  each  other. 

In  Fig.  22  let  us  suppose  that  B  is  a  bar  of  soft  iron,  bent  into 
the  shape  shown,  encircled  by  a  coil  of  wire,  also  in  manner  shown, 
and  that  M  is  a  strip  of  magnetized  iron,  freely  suspended,  with  its 


Fig.  23. 


north  pole  N  between  the  ends  of  the  iron  bar.  If  a  current  of 
electricity  be  sent  through  the  wire  in  the  .direction  indicated  by  the 
arrows,  the  bar  will  become  a  magnet  with  its  poles  as  marked. 
Hence,  as  like  poles  repel  and  unlike  poles  of  magnets  attract  each 
other,  the  north  pole  of  the  magnet  M  will  be  attracted  to  S  and 
repelled  from  N. 

Now  if  the  direction  of  the  current  be  reversed,  as  shown  by  the 
arrow  in  Fig.  23,  it  will  of  course  traverse  the  coil  and  go  around 
the  bar  in  a  direction  opposite  to  that  shown  in  Fig.  22.  Conse- 
quently, as  the  polarity  of  the  bar  is  determined  by  the  direction  of 
the  current  around  it,  its  polarity  will  be  changed,  and  the  poles 


THE  QUADRUPLEX.  33 

will  now  be  as  marked  in  Fig.  23.  Therefore  the  magnet  M  will 
now  be  repelled  from  its  last  position  and  attracted  to  the  other 
side,  as  shown.  Thus  we  can  see  that  as  often  as  we  change  the 
direction  of  the  current  around  the  bar,  we  change  the  position  of 
the  poles  of  the  bar,  and  at  the  same  time,  by  the  alternate  attrac- 
tion and  repulsion,  change  the  position  of  the  magnet  M  suspended 
between  the  poles  of  the  bar.  It  follows  that  if  we  cause  the  mag- 
net M  to  control  a  local  circuit,  and  provide  an  instrument  to 
reverse  the  direction  of  the  current,  we  have  the  necessary  condi- 
tions for  a  system  of  telegraphy,  and  this  principle  is  taken  advan- 
tage of  in  the  polar  duplex,  by  means  of  the  polar  relay  and  pole 
changer. 

THE  POLAR  RELAY. 

The  polar  relay  is  constructed  with  a  view  of  complying  with  the 
above  conditions. 

When  an  iron  bar  is  magnetized  by  electricity  circulating  around 
it,  it  is  termed  an  electro-magnet. 

Fig.  24  gives  a  front  view  of  a  polar  relay. 

P  is  a  curved  piece  of  steel,  which  is  permanently  magnetized  to 
the  polarity  marked.  E  M\&  an  electro-magnet,  the  core  or  bar  of 
which  is  somewhat  similar  in  shape  to  the  bars  shown  in  Figs.  22 
and  23,  but  wound  differentially.  This  electro-magnet  is  screwed 
firmly  to  the  south  pole  of  the  permanent  magnet.  The  armature 
is  a  soft  iron  strip  or  lever  hinged  at  one  end  to  the  north  pole  of 
the  permanent  magnet  P,  as  shown  in  dotted  lines,  its  other  end 
projecting  between  and  beyond  the  poles  of  the  electro-magnet 
E  M. 

Where  there  is  no  current  traversing  the  coils  of  the  electro-mag- 
net E  M,  the  poles  of  its  core  become,  by  induction,  the  south  poles 
of  the  permanent  magnet  P.  Likewise  the  outward  end  of  the 
lever  M.  has  become  and  remains  the  north  pole  of  the  permanent 
magnet  P.  Thus  the  lever  M,  when  adjusted  in  the  center,  will  be 
attracted  equally  by  either  end  of  the  electro-magnet,  as  both  of  its 
ends  are,  at  present,  south  poles. 


34 


THE  Q ITADR  UPLEX. 


When  a  current  is  sent  thrc .  jh  one  coil  of  the  electro-magnet  E 
M,  the  electro-magnetism  thus  generated  in  its  core,  being  of 
greater  strength,  will  overcome  the  magnetism  induced  by  the  per- 
manent magnet  P,  and  the  poles  will  be  established  according  to 
the  direction  of  the  current  around  the  core.  The  polarity  of  the 
lever  M  will,  however,  remain  constant,  and  it  will  be  attracted 


Fig.  24. 

and  repelled  by  the  alternate  changes  of  the  polarity  in  the  electro- 
magnet, and,  as  the  lever  is  provided  with  a  contact  point  to  break 
and  close  the  local  circuit  shown  in  the  diagram,  a  signal  will  be 
recorded  on  the  local  sounder  at  each  change  of  the  direction  of  the 
current  around  the  core  of  the  electro-magnet. 


CHAPTKR  VI. 

THE  POLAR  DUPLEX. 

Fig.  25  is  a  diagram  of  the  polar  duplex  set  up  at  both  ends. 

For  the  purpose  of  illustration,  we  shall  speak  of  the  currents  as 
circulating  around  the  cores  of  the  polar  relays  in  a  direction  from 
right  to  left,  or  left  to  right,  as  the  case  may  be ;  and,  in  the  dia- 
gram, the  preponderance  of  the  current  in  either  of  those  direc- 
tions may  be  supposed  to  have  magnetized  the  cores  to  the  polari- 
ties marked. 

A  and  A'  are  pole  changers,  R  and  R'  are  polar  relays.  B  is  a 
battery  having,  in  the  present  position  of  pole  changer  A,  its  posi- 
tive pole  to  line.  B1  is  another  battery  having,  in  present  position 
of  pole  changer  A',  its  negative  pole  to  line.  C and  C'are  condens- 
ers adjusted  to  give  a  static  discharge  equal  to  that  from  the  line 
at  the  moment  of  the  change  of  the  battery  polarities,  and  thus 
prevent  a  "  kick  "  similar  to  that  mentioned  in  th.e  Stearns  duplex. 
H  and  H'  are  rheostats  adjusted  to  equal  the  resistance  of  the  line 
wire.  The  electro-magnets  of  the  polar  relays  R  and  R'  are  wound 
differentially.  Hence  a  current  from  battery  B  (supposing  for  the 
moment  that  there  is  no  battery  at  the  distant  end)  will  divide  at 
the  split  S  in  two  equal  portions,  each  portion  we  shall  say  with  a 
strength  of  2,  as  explained  in  the  Stearns  duplex,  one  portion 
going  to  the  ground  through  the  line,  and  the  other  to  the  ground 
through  the  rheostat  H,  in  opposite  directions  around  the  core  of 
the  relay  R,  producing  no  magnetism  in  it. 

If  now  we  suppose  that  battery  B'  be  placed  in  the  circuit,  with 
its  negative  pole  to  the  line,  it  will  give  the  current  traversing  the 
line  coil  a  of  R,  from  left  to  right,  a  strength  of  4,  and  this  addi- 
tional strength  overcoming  the  strength  of  2  in  coil  b  will  mag- 
netize the  core  of  R  to  the  polarity  marked,  consequently  the 


36 


THE  QUADRUPLEX. 


THE  qUADRUPLEX.  37 

outward  end  of  lever  M  being  a  north  pole  will  be  attracted  to  S  and 
repelled  from  N.  A  somewhat  similar  effect  takes  place  in  relay 
R'.  The  positive  current  from  B  is  augmented  by  the  negative 
current  of  B'  and  thus  there  is  a  current  of  a  strength  of  four  trav- 
ersing coil  a'  and  going  around  the  core  of  R'  from  right  to  left, 
also  .magnetizing  it  to  the  polarity  marked  and  attracting  the 
lever  M.1 

Now,  if  while  the  negative  pole  of  battery  B'  is  still  to  the  line, 
we  change  the  polarity  of  the  home  battery  B  by  opening  the  pole 
changer  A,  what  will  be  the  effect  on  the  home  relay  R  ?  It 
should  be  nothing.  Let  us  see,  and  here  the  reader  is  recom- 
mended to  draw  for  himself  diagrams  corresponding  to  the  conse- 
quent changes.  This  change  puts  the  negative  pole  of  battery  B 
to  the  line.  Thus  batteries  B  and  B'  are  now  opposed  to  each 
other,  and,  being  of  equal  strength,  there  is  no  flow  of  current 
through  the  line  coil  a  of  relay  R,  but  as  the  direction  of  the  cur- 
rent of  B  is  changed,  and  while  it  is  true  that  there  is  now  no  cur- 
rent on  the  line  coil  of  jR,  there  is  a  current  with  a  strength  of  2 
flowing  in  from  the  rheostat  to  the  ground  through  coil  5,  and,  as  it 
thus  flows,  we  may  see  that  the  electricity  is  still  going  around  the 
core  of  R,  in  a  direction  similar  to  that  in  which  it  was  circulating 
before  the  change  of  polarity  at  -5,  namely  from  left  to  right,  and 
hence  the  polarity  of  the  core  is  unchanged,  and  the  lever  M  re- 
mains as  before.  This  shows  that  the  magnetic  polarity  of  the 
home  differential  polar  relay  is  not  affected  by  the  changes  of  polar- 
ity in  the  home  battery. 

Let  us  now  examine  the  effect  on  the  relay  R  of  a  change  of 
polarity  in  battery  B'.  It  should  reverse  the  magnetic  polarity  of 
the  core  of  relay  R.  The  negative  pole  of  battery  B'  has  been  to 
the  line.  It  will  now  be  the  positive  pole.  Let  B  have  positive 
pole  to  line  as  in  Fig.  25.  In  this  position,  the  positive  pole  of  B 
now  neutralizes  the  positive  pole  of  5,  and  therefore  there  is  no 
flow  through  the  line  coil  a,  but  there  is  a  current  of  a  strength  of 
2  now  flowing  through  the  rheostat  ff  to  the  ground  through  the 
coil  6,  and  as  this  current  is  circulating  around  the  core  in  an  oppo- 


38  THE  QUADRUPLEX. 

site  direction  to  that  in  which  the  previous  magnetizing  current  had 
been  flowing,  namely  from  right  to  left,  the  polarity  of  R  is  now 
changed,  whereby  the  lever  M  is  repelled  from  its  former  position 
and  attracted  to  the  other  end  of  the  core.  Thus  we  observe  that 
the  relay  R  responds  to  every  change  of  the  polarity  at  the  distant 
end  of  the  line,  regardless  of  the  polarity  of  the  home  battery  B. 
It  is  needless  to  add  that  the  relay  R'  will  in  a  like  manner  respond 
to  every  change  of  polarity  in  battery  B.  Such  being  the  case,  we 
may  simultaneously  change  the  polarity  at  each  end  as  frequently 
as  desired,  and  the  various  signals  will  be  recorded  appropriately. 

There  is  probably  nothing  in  the  operation  of  the  polar  duplex 
or  quadruplex  more  difficult  of  comprehension  to  the  beginner  than 
the  effect  produced  by  the  placing  of  similar  poles  of  batteries 
against  each  other.  For  instance,  if  we  take  a  battery  of  100  cells 
at  one  end  of  a  line  and  one  of  50  cells  at  the  other  end,  and  place 
the  positive  poles  of  each  battery  to  the  line,  there  will  be,  roughly 
speaking,  a  strength  on  the  line  equal  to  that  from  a  single  battery 
of  50  cells,  and  the  beginner  is  generally  at  a  loss  to  understand 
what  becomes  of  the  strength  of  the  remaining  100  cells.  To  tell 
him  that  50  cells  at  one  end  are  neutralized  by  50  at  the  other  end 
is  not  always  satisfactory. 

Perhaps  the  following  homely  illustration  will  make  it  somewhat 
plainer : 

Let  us  imagine  a  railway  train  with  a  locomotive  at  each  end  of 
the  train,  each  locomotive  to  have  a  strength  of  50.  If  we  oppose 
the  strength  of  these  engines  against  each  other,  we  know  that  the 
train  will  not  move.  If  now  we  bring  another  locomotive  having 
also  a  strength  of  50  and  place  it  at  one  of  the  ends,  the  train  will 
now  move,  but  urged  only  by  a  strength  in  all  of  50,  although  there 
is  a  locomotive  force  of  150  being  exerted  on  the  train.  In  other 
words,  the  power  of  two  of  the  locomotives  is  consumed,  one  in 
opposing  another  of  equal  power,  as  in  the  case  of  the  battery 
referred  to. 

We  may  indeed  use  the  same  homely  illustration  in  a  variety  of 
ways  to  show  the  action  of  electricity  on  a  wire. 


THE  QUADRUPLEX.  39 

We  have  heretofore  spoken  of  the  current  or  flow  of  electricity 
when  \ve  have  meant  to  signify  the  direction  in  which  the  electricity 
acts.  Thus,  we  have  said  that  when  the  positive  pole  of  a  Battery 
is  placed  to  the  line  its  action  is,  invariably,  toward  the  line,  as 
shown  by  a  galvanometer,  and  the  action  of  a  negative  pole  when 
placed  to  the  line  is  as  invariably  inward  from  the  line. 

Now,  if  we  say  that  when  a  locomotive  is  pushing  the  train  it  is 
exerting  a  positive  strength,  and  when  it  is  pulling  the  train  that  it 
is  exerting  a  negative  strength,  it  is  easy  to  understand  that  if  we 
cause  the  engine  at  one  end  of  the  train  to  exert  a  positive  and  the 
one  at  the  other  a  negative  strength  upon  the  train,  there  will  be 
the  full  effect  of  two  engines  acting  upon  the  train  in  the  same  di- 
rection, and  the  train  will  move  accordingly. 

On  the  contrary,  if  we  cause  both  to  exert  a  positive  strength, 
or  both  to  exert  a  negative  strength  upon  the  train,  that  is  to  say, 
if  we  cause  them  both  to  push  or  both  to  pull  the  train,  it  will  not 
move. 

Thus  it  is,  practically,  with  electric  batteries  at  each  end  of  a 
wire,  with  regard  to  their  effect  on  electro-magnets.  If  we  place 
their  positive  poles  to  the  line,  the  action  of  each  is  toward  the  line 
and  no  effect  is  produced.  If  we  place  their  negative  poles  to  the 
line,  their  action  is  inward  from  the  line  and  no  result  follows ;  but 
if  we  put  the  negative  pole  of  the  battery  to  the  line  at  one  end 
and  the  positive  pole  at  the  other  end,  the  strength  of  both  is  now 
virtually  being  exerted  in  the  same  direction  on  the  wire  and  the 
strength  of  the  two  batteries  is  obtained. 

In  addition  to  the  weight  of  the  train  which  the  engines  have  to 
move,  they  also  have  to  use  part  of  their  strength  in  moving  them- 
selves. . 

The  resistance  which  a  battery  has  to  overcome  in  its  own  ele- 
ments and  which  is  called  its  internal  resistance,  as  before  stated, 
may  be  likened  to  the  weight  of  the  engine.  Thus  the  lower  the 
internal  resistance  of  a  battery  can  be  made  without  reducing  its 
electro-motive  force,  the  gfeater  will  be  the  resultant  strength  up^n 
a  given  wire. 


CHA.PTBR  VII. 

THE  QUADRUPLEX. 

Having  studied  the  principles  upon  which  the  Stearns  and  polar 
duplexes  are  operated,  it  will  perhaps  render  the  study  of  the 
quadruplex  less  complex  if  we  first  examine  separately  the  modifi- 
cations necessary  to  the  combination  of  these  duplex  principles  in 
the  quadruplex. 

We  have  seen  that  the  Stearns  duplex  is  operated  primarily  upon 
two  conditions,  namely,  battery  to  the  line  and  no  battery  to  the 
line.  Consequently,  there  are  intervals  in  the  working  of  this  du- 
plex when  there  is  no  current  on  the  line.  It  will  at  once  suggest 
itself  to  the  student  that  such  a  condition  as  this  on  the  polar  du- 
plex (which  is  operated,  not  by  a  withdrawal  of  the  current  at  any 
time,  but  by  a  change  in  its  direction,)  would  render  it  inopera- 
tive. Therefore,  if  we  are  to  combine  these  two  principles,  we 
must  in  some  way  preserve  at  all  times  a  current  on  the  wire  to 
insure  the  working  of  the  polar  system. 

The  manner  in  which  this  is  accomplished  will  be  shown  in  the 
description  of  Figs.  27  and  28. 

We  have  seen  also  that  the  polar  relay  in  the  polar  duplex  sys- 
tem is  actuated  by  the  reversals  of  polarity,  and  that  the  neutral 
relay  in  the  Stearns  duplex  is  attracted  by  a  current  of  either 
polarity. 

The  following  illustration  will  explain  how  these  different  results 
are  obtained  on  the  same  wire  at  the  same  time,  as  they  are  in  the 
quadruplex  system,  without  interfering  with  each  other. 

In  Fig.  26  we  have  a  single  wire  encircling  the  cores  of  a  neutral 
and  a  polarized  relay  in  such  a  manner  that  a  positive  current 
with,  we  will  again  assume,  a  strength  of  2  from  battery  C  will 
pass  around  their  cores  in  a  direction  tending  to  magnetize  them 


THE  qUADRUPLEX. 


41 


42 


THE  QUADRVPLEX. 


to  the  polarity  marked — that  is  to  say,  if  we  are  looking  at  the  ends 
marked  $  (the  south  pole),  the  current  will  be  circulating  around 
the  cores  in  a  direction  similar  to  that  of  the  hands  of  a  watch. 
Hence  the  north  pole  of  lever  M is  attracted  to  S  and  repelled  from 
N,  and  the  armature  M1  is  attracted  to  both  poles  of  its  magnet,  as 
in  the  ordinary  Morse  relay  or  sounder.  Let  us  now  increase  the 
tension  of  the  retractile  spring  of  M'  just  enough  to  overcome  the 
attraction  of  the  magnetism  generated  in  R'  by  the  existing  cur- 
rent having  a  strength  of  2 ;  so  that  M'  is  withdrawn  from  R'. 
If  now,  by  means  of  a  pole  changer,  we  change  the  direction  of  the 


J) 


Illlllllll 


Fig.  27. 

current  from  battery  (7,  we  shall  find  that  the  poles  of  both  relays 
have  changed,  and  that  the  armature  or  lever  M  has  changed  its 
position  because  of  this ;  but  we  find  that  the  armature  M'  of  the 
neutral  relay  is  unmoved,  being  still  retained  by  the  retractile 
spring,  for  the  reason  that,  although  the  direction  of  current  has 


THE  QUADRUPLEX.  ^ 

changed,  its  strength  has  not,  and  consequently  the  strength  of  the 
magnetism  of  R1  has  not  been  augmented. 

Again  referring  to  Fig.  26.  If  now  we  increase  the  strength  of 
the  current  from  2  to  say  4,  without  changing  the  direction  of 
the  current,  we  find  that  the  increased  magnetism  in  relay  Rf  has 
attracted  armature  M',  but  the  only  effect  produced  on  the  lever  M, 
by  the  additional  strength  of  current,  is  that  it  is  more  strongly 
attracted  to  S,  and  repelled  from  N. 


line 


Fig.  28. 


To  carry  the  illustration  one  point  further.  If,  while  the  strength 
of  4  is  on  the  line,  we  change  the  direction  of  the  current,  we  find 
that  the  lever  M  has  again  been  affected,  and  that  it  has  changed 
its  position,  while  the  armature  M'  is  unmoved  for  the  reason  be- 
fore given. 

The  foregoing  embodies  the  manner  in  which  the  two  main  prin- 
ciples of  the  duplexes  are  combined  in  the  quadruplex. 

In  our  study  of  the  Stearns  duplex  we  learned  that  the  function 


44  THE  QUADRUPLEX. 

of  the  transmitter  was  to  alternately  place  the  line  to  the  battery 
arid  to  the  ground.  In  the  quadruplex  system  its  function  is  to 
alternately  place  the  whole  battery  and  a  small  portion  of  the  bat- 
tery to  the  line,  in  the  manner  hereafter  described. 

The  armature  of  the  neutral  relay  in  the  quadruplex  is  adjusted 
so  that  the  smaller  portion  of  the  distant  battery  will  have  no  prac- 
tical effect  upon  it,  and  as  this  smaller  portion  of  the  current  is  re- 
duced to  the  lowest  point  compatible  with  the  effective  working  of 
the  polar  relay,  it  follows  that,  as  the  polar  relay  is  designed  to 
work  uninterruptedly  and  smoothly  through  all  changes  in  the 
strength  of  current,  it  should  be  a  more  sensitive  instrument  than 
the  neutral  relay,  and  such  is  the  case 

As  sensitiveness  is  not  so  much  desired  in  the  neutral  relay,  its 
core  is  made  very  short,  and  it  is  wound  with  coarser  wire  than 
the  polar  relay,  hence  it  has  fewer  convolutions  of  wire  around  its 
cores  than  the  latter  instrument.  Therefore  a  given  strength  of 
current  will  have  much  more  magnetic  effect  upon  the  polar  relay 
than  upon  the  neutral  relay.  But  apart  from  the  above  noted  dif- 
ferences in  the  construction  of  the  two  instruments  the  fact  that  the 
armature  of  the  polar  relay  aids  in  its  own  movements  is  an  impor- 
tant factor  in  rendering  it  more  sensitive  than  the  neutral  relay. 

The  usual  resistance  of  each  coil  of  the  polar  relay  is  about  400 
ohms,  that  of  the  neutral  relay  200  ohms. 

Figs.  27  and  28  show  the  manner  in  which  the  transmitter 
changes  the  strength  of  current  on  the  wire.  In  the  figures  the  in- 
struments unnecessary  to  show  this  action  are  omitted. 

Fig.  27  shows  a  wire  running  from  the  earth  to  the  nega- 
tive pole  of  battery  B.  There  is  also  another  wire  from  one  of  the 
positive  cells  of  the  battery  which  runs  from  P  to  the  bar  of  the 
transmitter,  which  is  represented  as  open  Another  wire  is  led  from 
the  positive  end  of  the  battery  to  the  post  D  of  the  transmitter, 
and  the  line  wire  is  connected  as  heretofore  to  the  tongue  of  that 
instrument.  The  same  connections  occur  in  Fig.  28.  In  Fig.  27, 
if  we  follow  the  circuit  through  the  full  battery  to  post  D,  we  can 
see  that  it  leads  to  an  open  point  near  X,  so  that  no  current  can 


THE  QUADRUPLEX.  45 

pass.  On  the  contrary,  if  we  follow  the  wire,  which  taps  the  bat- 
tery at  P,  we  may  see  that  there  is  here  a  route  for  the  current 
through  the  bar  to  the  tongue  of  the  transmitter,  and  thence  to  the 
line ;  but  in  this  case  it  is  plain  that  that  portion  of  the  battery  be- 
tween P  and  F  is  cat  off,  and  thus  only  a  small  portion  of  the  bat- 
tery is  placed  to  the  line,  hence  the  neutral  or  No.  2  relay  at  dis- 
tant end  will  not  have'attracted  its  armature.  Referring  now  to 
Fig.  28,  the  transmitter  is  shown  as  closed.  The  figure  shows 
that  the  bar  of  the  transmitter  has  broken  contact  with  the  tongue 
at  X,  but  instead  the  tongue  has  made  contact  with  the  post  D'. 
Thus  the  full'  battery  is  now  placed  to  the  line,  and  the  armature 
of  neutral  relay  at  distant  end  will  be  attracted  to  the  core.  Thus, 
as  often  as  the  transmitter  is  opened  or  closed,  the  full  battery,  or 
only  a  portion  thereof,  will  be  placed  to  the  line,  but  in  either  case 
there  must  always  be  sufficient  current  left  on  the  line  to  operate 
the  polar  relays. 

Fig.  29  shows  the  theoretical  manner  in  which  the  various  prin- 
ciples that  we  have  been  considering  in  the  duplexes,  etc.,  are 
grouped  to  produce  the  Edison  quadruplex. 

P  and  P'  are  pole  changers,  2*  and  T'  are  transmitters,  -ZV^and  N' 
are  neutral  relays,  R  and  Rf  are  polarized  relays.  The  manner  in 
which  the  relays  are  wound  in  the  figure  is  not  the  precise  method 
adopted  in  actual  practice,  but  the  result  is  the  same.  We  have 
chosen  the  manner  of  winding  shown  in  the  diagram  with  a  view  to 
making  the  action  of  the  current  on  the  cores  of  the  electro-magnets 
easier  of  comprehension. 

The  figure  shows  the  quadruplex  theoretically  set  up  at  both 
ends,  namely  A  and  B. 

At  A  the  keys  of  both  sides  are  supposed  to  be  closed,  at  B 
open. 

It  might  be  supposed  that  having  discovered  the  foregoing  princi- 
ples of  electricity  and  magnetism,  it  only  remained  for  the  inventor 
to  manufacture  and  arrange  the  instruments  necessary  to 
produce  the  increase  and  decrease  of  current  and  the  changes  of 
polarity,  with  instruments  to  respond  to  those  changes,  when  he 


Fig.  29.— THEORETICAL  DIAGRAM  OF  QUADRUPLED 


THE  QUADRUPLEX.  47 

would  have  a  successful  working  quadruplex  system,  and  probably 
this  was  the  conclusion  arrived  at  by  many  inventors  and  experi- 
menters, but  actual  experience  taught  them  that  more  than  this  was 
required.  For  instance,  it  was  found,  as  in  the  duplexes,  that 
between  each  change  of  polarity  of  the  home  battery  the  line  on 
long  circuits  gave  back  a  return  or  static  discharge,  which,  by  mo- 
mentarily charging  the  cores  of  the  relay  with  opposite  magnetism, 
produced  a  click  in  the  home  relays,  which  rendered  the  signals 
from  the  distant  end  unreadable.  Hence  it  was  necessary  to  insert 
in  the  balancing  wire  between  the  rheostats  and  the  relays  a  con- 
denser ((7  and  0'  as  in  figure),  which  would  accumulate  a  quantity 
of  electricity  equal  to  that  accumulated  on  the  line,  and  which 
would  also  discharge  itself  during  the  interval  between  the  reversals 
of  the  poles  of  the  batteries,  and  thus  neutralize  the  effect  of  the 
line  discharge.  This  was  found  effectual  on  comparatively  short 
circuits,  but  on  longer  circuits  it  became  apparent  that  the  condenser 
discharged  itself  before  the  Mne  had  completely  discharged,  and 
thus  the  result  desired  was  not  quite  attained.  This  necessitated 
the  insertion  of  the  resistance  coils  H"  and  H'"  between  the  artifi- 
cial wire  of  the  rheostat  and  the  condenser,  to  retard  the  discharge 
of  the  latter,  which  proved  successful. 

It  was  also  seen  that  at  every  motion  of  the  transmitter  which 
cuts  off  the  larger  portion  of  the  home  battery,  the  internal  resist- 
ance of  said  portion  of  the  battery,  which  is  equal  to  from  two  and 
one  half,  to  three  ohms  per  cell,  was  taken  from  the  wire,  thus  de- 
ducting from  the  total  resistance  of  the  line,  say,  from  100  to  500 
ohms,  according  to  the  number  of  cells  cut  off.  This  would  have 
produced  a  variation  in  the  resistance,  which,  especially  in  bad 
weather,  when  there  was  a  small  working  margin  of  current,  would 
more  than  likely,  by  making  the  balance  at  the  distant  end  un- 
steady, prevent  the  successful  working  of  the  quadruplex.  To  com- 
pensate for  this,  resistance  coils  (A  and  A'),  equal  to  the  internal 
resistance  of  the  cells  thus  cut  off,  were  inserted  between  the  taps 
Z  and  Z'  and  the  bars  of  the  transmitters. 

Another  obstacle  to  the  working  of  the  quadruplex  was  also  en- 


48  THE  QUADHUPLEX. 

countered.  It  was  found  that  while  the  full  battery  was  to  the  line 
(as  at  A  in  the  figure,  and  the  armature  of  neutral  relay  N'  at  dis- 
tant end  B  was  thus  attracted  to  its  magnet),  if  the  polarity  at  sta- 
tion A  was  changed,  thereby,  as  we  have  seen,  for  an  instant  taking 
off  the  battery  at  JL,  from  the  line,  at  that  instant  the  retractile 
spring  of  the  neutral  relay  N'  would  tend  to  withdraw  the  armature 
from  the  magnet,  thus  making  a  false  "clip,"  and  breaking  up  the 
regular  signals.  To  obviate  this  trouble  the  local  contact  of  the 
neutral  relay  is  placed  on  the  back  stop,  and  a  repeating  sounder 
is  in  many  cases  also  added  to  the  local  circuit,  as  is  shown  in  cut 
(Fig.  30).  The  instant  when  the  battery  is  cut  off  from  the  line 
is,  however,  of  so  short  duration  that  the  neutral  relay  has  appar- 
ently not  time  to  become  entirely  demagnetized,  so  that  it  regains 
its  maximum  magnetism  and  re-attracts  its  armature  before  the  lat- 
ter has  made  a  firm  contact  on  the  back  stroke,  and  hence  the  re- 
peating sounder  is  not  fully  charged,  consequently  its  armature  is 
not  sufficiently  affected  by  the  false  signals  to  interfere  with  the 
regular  sounder,  which  is  operated  by  this  armature,  and  thus  the 
signals  intended  for  the  neutral  relay,  although  undoubtedly  muti- 
lated in  the  course  of  transmission  while  the  polar  side  is  in  opera- 
tion, are  received,  by  means  of  the  above  arrangement,  unbroken, 
and  on  the  front  stop  of  the  regular  local  sounder.  When  the  re- 
peating sounder  is  dispensed  with,  as  it  is  now  on  many  circuits, 
the  connections  are  so  arranged  at  the  distant  end  that  in  reality 
the  transmitter  sends  out  the  signals  on  the  "  back  stroke,"  but  as 
the  local  contact  point  of  the  neutral  relay  is  placed,  as  before 
stated,  on  the  back  stop,  the  receiving  operator  receives  the  signals 
as  usual. 

It  may  be  asked,  why  is  not  the  polarized  relay  affected  in  the 
same  manner  at  the  instant  of  change  of  polarity  of  the  distant  bat- 
tery ?  In  fact  it  is,  that  is  to  say,  it  also  partly  loses  the  magnet- 
ism due  to  the  distant  battery,  but  at  that  instant  the  permanent 
magnetism  of  the  polarized  relay  comes  into  operation,  and,  as  has 
been  shown,  as  the  ends  of  the  core  of  the  electro-magnet  of  the 
polarized  relay  are  in  that  case  both  south  poles,  the  north  pole  of 


THE  QUADRUPLED.  49 

its  armature  will  be  retained  in  its  present  position  until  the  actual 
change  of  polarity  ensues.  But  aside  from  this,  there  would  be  no 
tendency  on  the  part  of  the  armature  of  the  polarized  relay  to  leave 
its  existing  position,  owing  to  the  fact  that  its  inertia  would  be 
sufficient  to  keep  it  where  last  placed ;  it  being,  as  we  have  said, 
the  retractile  spring  of  the  neutral  re7ay  which  tends  to  draw  it 
away  at  the  time  referred  to. 

Even  after  all  these  defects  were  discovered  and  remedied  the 
quadruplex  was  not  yet  a  success,  and  it  was  not  until  after  many 
months  of  actual  working  and  experiment  that  the  modifications  of 
the  instruments  first  used,  which  have  brought  the  system  to  its 
present  state  of  usefulness,  were  invented  and  applied. 

The  polar  side  of  the  quadruplex  is  frequently  called  the  No.  1 
side  ;  and  the  increase  and  decrease  of  strength  side,  the  No.  2  side. 

The  polar  relay  and  neutral  relay  are  also  spoken  of  as  the  No.  1 
and  No.  2  relay,  respectively. 

When  the  compound  polarized  relay  was  used  on  the  No.  2  side 
of  the  quadruplex  it  was  found  that  a  condenser  inserted  between 
that  relay  and  the  polar  relay,  by  absorbing  or  counteracting  the 
extra  currents  generated  by  the  demagnetization  of  the  cores  of  the 
relay,  steadied  that  relay  somewhat  during  the  changes  of  polarity, 
but  as  the  utility  of  that  condenser  seems  to  have  ceased  with  the 
introduction  of  the  short  core  relay,  arid  as  it  is  now  dispensed 
with  entirely  on  many  circuits,  we  have  not  included  it  in  the  dia- 
grams. 

There  now  remains  but  little  to  be  said  as  to  the  working  of  the 
quadruplex  if  the  reader  has  followed  us  by  the  different  stages 
that  have  led  up  to  this  point. 

We  shall,  however,  for  the  benefit  of  the  beginner,  trace  the 
course  of  the  circuit  in  Fig.  29.  Beginning  at  E,  station  J.,  the  cir- 
cuit is  led  to  the  bar  of  the  pole  changer,  thence  via  the  upper 
tongue  of  the  same  to  the  negative  pole  of  the  battery  at  -4,  through 
the  entire  battery  to  the  post  and  tongue  of  the  transmitter,  to  the 
lower  tongue  of  the  pole  changer  and  thence  to  the  disc  thereof. 
Here  the  circuit  is  divided,  one  portion  going  through  the  neutral 


50  THE  QUADRUPLEX. 

relay,  the  polar  relay,  and  to  the  line  and  to  the  ground  at  distant 
end  B.  The  other  portion  of  the  circuit  goes  through  the  neutral 
and  polar  relays  and  through  the  rheostat  ^Tto  the  ground. 

Beginning  at  E,  station  .5,  the  circuit  is  led  to  the  bar  of  the 
pole  changer,  thence  to  the  lower  tongue  of  that  instrument,  to  the 
positive  pole  of  battery  at  -B,  through  the  small  end  of  this  battery 
to  Z,  thence  to  the  bar  of  T',  and  via  the  tongue  of  T  to  the  upper 
tongue  of  P'  and  to  the  disc  thereof,  where  the  current  divides  as 
at  A. 

In  the  present  positions  of  the  transmitters  and  pole  changers  at 
both  ends,  the  polar  relays  and  neutral  relays  are  attracted  or  with- 
drawn, as  shown.  That  such  results  are  produced  by  these  conditions 
is  well  known  to  all  who  have  had  practical  acquaintance  with  the 
working  of  the  quadruplex,  but  for  the  information  of  those  who  wish 
to  trace  the  question  we  shall  endeavor  to  analyze  one  or  two  of  the 
many  combinations  that  occur  on  the  quadruplex,  which  could  not 
occur  on  either  the  Stearns  or  the  polar  duplex  alone,  promising 
the  beginner,  however,  that  it  may  require  considerable  study  on  his 
part  to  thoroughly  understand  them.  We  will  suppose  that  the 
small  ends  of  both  batteries  consist  of  50  cells  and  the  large  ends 
100  cells  each,  making  the  total  of  each  battery  150  cells.  Thus,  as 
the  full  battery  at  A  is  to  the  line  with  its  positive  pole,  and  as  it 
is  augmented  by  50  cells  from  the  negative  pole  of  that  at  B,  there 
is  virtually  a  strength  from  200  cells  flowing  through  the  coil  a  of 
R,  from  left  to  right  to  the  line  and  a  strength  from  150  cells  flow- 
ing through  coil  b  from  right  to  left  to  the  rheostat.  (It  is  of 
course  understood  that  we  speak  of  a  strength  of  200  cells  on  the 
line  merely  for  purpose  of  illustration.)  This  attracts,  as  we  see, 
the  armature  of  the  neutral  relay  N1  at  B,  and  the  negative  pole  of 
battery  at  B  being  to  the  line,  the  armature  of  R  is  as  placed.  Let 
us  now  close  the  pole  changer  P1  at  B.  This  places  50  cells  of  posi- 
tive polarity  to  the  line  at  this  point  B,  and  these  50  cells  oppose 
and  neutralize  50  positive  cells  of  battery  at  A,  making  the  total 
strength  of  current  now  on  the  line  equal  to  100  cells.  This  now 
leaves,  therefore,  a  strength  of  100  cells  flowing  through  coil  a  of 


THE  QUADRUPLEX.  51 

the  polar  relay  R  to  line  from  left  to  right,  while  there  is  now  a 
strength  of  150  cells  flowing  from  the  battery  at  A  through  the 
coil  b  of  the  polar  relay  to  rheostat  from  right  to  left.  This  leaves 
a  preponderance  of  current  flowing  in  the  latter  direction,  and,  con- 
sequently, the  polarity  of  the  polar  relay  R  is  reversed,  and  its  ar- 
mature changes  its  position. 

This  position  of  the  pole  changer  at  j5,  as  we  saw,  reduces  the 
strength  of  current  coming  from  battery  at  A  to  100  cells.  Why, 
therefore,  does  not  the  retractile  spring  withdraw  the  armature  of 
N,  which  we  saw  was  held  to  the  armature  by  the  full  battery  of 
J.,  viz.,  150  cells  being  to  the  line?  It  is  because  there  is  now  a 
strength  of  50  cells  from  the  positive  pole  at  B  going  through  the 
neutral  relay  N'  to  the  rheostat  and  ground,  and  this  strength  of 
50  cells,  owing  to  the  manner  in  which  the  coils  are  wound,  is  cir- 
culating around  the  core  of  the  relay  in  the  same  direction  as  that 
of  the  current  of  100  cells  strength  from  J.,  thereby  still  preserving 
a  strength  of  150  cells  on  neutral  relay  M1 ,  and  of  course  this  ac- 
counts for  the  fact  that  its  armature  remains  attracted.  There  are 
many  such  combinations  continually  occurring  on  the  quadruplex, 
which  at  first  sight  would  seem  to  be  enough  to  entirely  prevent 
the  working  of  the  system,  but  an  analysis  of  each  combination  will 
prove,  what  is  known  to  be  the  case,  that  they  do  not  so  prevent. 

In  studying  the  combinations  that  occur  on  these  multiplex  sys- 
tems, it  should  be  remembered  by  the  beginner  that  the  currents 
which  flow  to  or  from  the  rheostat,  or  artificial  wire,  are  always  de- 
pendent on  the  home  battery.  If,  for  instance,  50  cells  of  positive 
polarity  be  placed  to  the  line  from  battery  at  B  in  Fig.  29,  a  posi- 
tive current  of  50-cells  strength  will  flow  to  the  ground  through 
the  rheostat,  even  though  a  positive  battery  of  150  cells  should  be 
opposed  to  the  same  battery  at  the  distant  end,  A.  In  other 
words,  the  wire  through  the  rheostat  may  be  considered  as  a  sepa- 
rate wire,  excepting  that  it  is  led  through  one  coil  of  the  various 
differential  relays. 

Fig.  30  is  a  diagram  showing  the  actual  connections  at  one  end 
of  a  quadruplex  system.  The  polar  relay  and  the  neutral  relay  are 


52  THE  QUADRUPLEX. 

shown  by  the  bare  coils.  The  repeating  sounder  previously  men- 
tioned adjoins  the  neutral  relay.  Q  is  the  resistance  to  compen- 
sate for  that  portion  of  the  battery  which  is  cut  out  when  the  small 
end  of  the  battery  is  to  the  line.  The  coil  G-  in  the  rheostat  R  is 
the  resistance — equal  to  the  internal  resistance  of  the  entire  bat- 
tery— which  is  placed  in  the  circuit  when  the  wire  is  grounded  for 
a  balance.  The  wire  is  grounded  for  this  purpose  by  turning  the 
three-button  switch  B  to  the  right.  It  will  be  noticed  that  this  ac- 
tion cuts  off  the  battery,  the  pole  changer  and  transmitter. 

Q'  is  the  resistance  placed  between  the  condenser  and  rheostat 
wire  on  long  circuits,  for  reasons  already  explained. 

The  route  of  the  circuit  in  the  present  position  of  the  pole  changer 
and  transmitter  is  traced  by  the  figures  1,  2,  3,  4,  etc.,  up  to  13,  where 
the  circuit  divides,  and  letters  then  show  the  route  to  ground 
through  the  rheostat. 

It  may  be  stated  in  passing  that  there  has  been  no  special  attempt 
made  in  these  diagrams  to  show  the  instruments  in  their  actual  re- 
lations to  each  other  as  to  size,  the  main  idea  being  to  present  the 
instruments  in  the  clearest  and  simplest  position.  Thus  the  rheo- 
stat box  is  shown  as  apparently  smaller  than  the  transmitter, 
whereas,  in  reality,  as  we  all  know,  it  is  several  times  larger. 

BALANCING  THE  QUADRUPLEX. 

To  balance  a  quadruplex,  ask  the  distant  station  to  ground  for 
you.  In  doing  so  he  cuts  out  his  pole  changer  and  entire  battery, 
as  may  be  seen  in  the  diagram  of  the  complete  quadruplex  with 
connections.  It  will  also  be  seen  that  in  grounding  he  interposes 
a  resistance  equal  to  the  internal  resistance  of  his  entire  battery, 
otherwise  when  he  again  cuts  in  his  battery  your  balance  would  be 
several  hundred  ohms  too  low,  according  to  the  size  of  his  battery. 
You  now  also  ground.  Now  the  wire  is  without  battery  at  either 
end.  Then  adjust  the  armature  of  the  polarized  relay  so  that  it 
will  stay  on  whichever  side  it  is  placed.  Now  cut  in  your  full  bat- 
tery and  insert  or  withdraw  plugs  from  your  rheostat  until  the  arma- 
ture of  the  polarized  relay  again  remains  on  whichever  side  placed, 


THE  QUADRUPLEX.  53 

this  showing  that  an  equal  strength  of  electricity  is  flowing  in  oppo- 
site directions  around  the  core  of  the  relay,  as  no  magnetic  effect  is 
produced,  and  proving  that  the  resistances  of  the  line  and  rheostat 
are  equal.  Now  open  and  close  the  pole  changer  and  note  the 
action  of  the  polar  relay.  If  it  responds  clearly  to  each  motion  of 
your  pole  changer,  you  either  have  too  much  or  not  enough  dis- 
charge from  your  condenser.  Therefore  adjust  your  condenser 
until  its  discharge  is  sufficient  to  neutralize  the  static  discharge 
from  the  line,  which  will  be  shown  by  the  failure  of  the  polarized 
relay  now  to  respond  to  the  movement  of  the  pole  changer. 

The  polar  duplex  is  balanced  in  the  same  manner  as  the  quadru- 
plex.  The  Stearns  duplex  is  balanced  by  asking  the  distant  station 
to  open  his  key,  which  is  virtually  asking  him  to  "  ground."  Then 
dot  on  your  own  key  and  adjust  your  rheostat  and  condenser  until 
your  relay  remains  passive  under  the  movements  of  your  trans- 
mitter. 


UITIVETISITT 


THE  QUADRUPLEX. 


CHAPTER  VIII. 

THE  DYNAMO-ELECTRIC  MACHINE  IN   RELATION  TO   THE 

QUADRUPLEX. 

BY    WM.    MAVER,    JR. 

Upon  the  introduction  of  the  dynamo-electric  machines  into  the 
Western  Union  building  as  a  means  of  supplying  electro-motive 
force,  it  was  found  necessary,  if  this  source  of  supply  was  to  be 
availed  of  in  the  working  of  the  polar  duplex  and  the  quadruplex 
systems,  to  alter  considerably  the  arrangement  of  the  instruments 
used  in  the  working  of  those  systems  by  the  gravity  battery. 

Before  proceeding  to  describe  these  alterations  it  will  perhaps 
be  well  to  interpose  the  following  description  of  the  manner  in 
which  the  dynamo  machines  supply  the  electro-motive  force  to  the 
various  wires.  The  description  will,  I  think,  tend  to  make  plainer 
some  of  the  statements  hereafter  made. 

I  may  state  that  this  account  of  the  dynamo  machines  is  taken 
almost  verbatim  from  an  article  on  the  Western  Union  building, 
written  by  me  some  time  ago,  for  The  Electrical  World. 

The  electro-motive  force  for  the  wires  leaving  the  Western  Union 
main  office  is  furnished  by  dynamo-electric  machines,  of  which  there 
are  fifteen  on  the  battery  floor,  in  series  of  five  machines.  Thus  there 
are  three  series.  Two  of  these  series  are  kept  in  operation  day  and 
night,  the  other  series  being  reserved  for  emergencies  or  to  allow 
of  necessary  repairs.  The  motive  power  for  these  machines  is  sup- 
plied by  three  safety  steam-power  engines  of  six  horse-power  each, 
which  derive  their  steam  from  boilers  in  the  sub-cellar.  Of  these 
series  or  gangs  of  five  machines,  one  machine  is  used  to  generate  a 
magnetic  field  for  itself  and  the  four  other  machines.  It  also  deter- 
mines the  polarity  of  the  series  according  to  the  direction  of  its  cur- 
rent around  the  field-magnets  of  the  other  machines.  One  of  the  act- 
ive series  supplies  negative,  the  other  positive,  polarity  to  the  wires. 


56  THE  QUADRUPLED 

The  polarity  of  the  spare  series  may  easily  be  changed  to  positive 
or  negative  by  means  of  a  switch  arranged  for  the  purpose  in  the 
battery  room. 

Four  grades  of  potential  are  furnished  from  each  series  of  these 
machines,  in  the  manner  hereafter  described. 

Artificial  resistances,  equal  to  three  ohms  per  volt,  composed  of 
coils  of  German  silver  wire  wound  on  cylinders  of  prepared  plaster  of 
paris,  are  interposed  between  each  machine  and  every  wire  leaving 
the  switch,  as  shown  in  the  engraving.  Thus  the  resistance  of  each 
coil  interposed  between  the  first  potential  and  the  wires  is  about 
200  ohms ;  between  the  second  potential  and  wires,  400  ohms ; 
between  the  third  potential  and  wire's,  600  ohms,  and  between 
the  fourth  potential  and  wires,  800  ohms.  These  coils  serve  to 
diminish  the  intensity  of  the  dynamo  current,  thereby  obviating 
sparks,  and  to  prevent,  in  a  measure,  the  burning  of  instruments  in 
case  of  the  short  circuiting  of  a  wire.  The  first,  second,  and  third 
potentials  are  conducted  to  the  main  switch,  the  first  and  second 
potentials  only  to  the  city  line  and  Long  Island  switch. 

The  fourth  potential  is  used  principally  to  supply  very  long  quad- 
ruplex  circuits,  such  as  those  to  Bangor,  Me. ;  Lynchburg,  Va.,  etc. 

Wires  having  an  average  resistance  of  about  3,000  ohms  are  sup- 
plied from  the  first  potential.  Those  having  an  average  resistance 
of  about  5,500,  from  the  second  potential.  The  third  potential  is 
mainly  used  for  duplex  and  quadruplex  circuits.  The  New  York  City, 
Brooklyn,  and  Jersey  City  wires,  being  generally  of  low  resistance, 
are  also  supplied  from  the  first  potential ;  but  the  resistances  of 
those  wires  are  increased  by  means  of  resistance  plugs,  inserted  at 
the  switch  in  their  circuits,  to  an  average  resistance  of  from  3,000 
to  4,000  ohms. 

The  illustration,  Fig.  31,  gives  a  top  view  of  one  series  of  the 
dynamo  machines,  showing  the  manner  in  which  the  several  poten- 
tials are  derived  and  the  method  of  interposing  the  artificial  resist- 
ance coils  previously  mentioned. 

A,  .B,  C,  _D,  and  E  are  the  five  dynamo  machines  of  one  series. 
A  is  the  feeder  which  furnishes  the  magnetic  fields  for  itself  and  the 


THE  QUADRUPLEX. 


57 


58  THE  QUADRUPLEX. 

four  other  machines.  A',  B',  C',  D',  and  E'  are  the  armature  coils  of 
each  machine.  The  rear  of  a  portion  of  one  section  of  the  main 
switch  in  the  operating  room  is  shown  above  the  machines.  To 
simplify  the  illustration,  neither  the  belting  gear  of  the  machinery 
nor  the  polarity  changing  switch  in  the  battery  room  are  shown. 

The  plaster  of  paris  cylinders,  around  which  the  artificial  resist- 
ance coils  are  wound,  rest  on  horizontal  strips  of  brass.  The  lower 
terminal  of  each  coil  is  attached  to  the  brass  support  and  the  upper 
terminal  is  conducted  to  a  small  disc  on  the  switch.  The  perpen- 
dicular strips  on  the  switch  are  each  connected  to  one  line  wire,  so 
that  by  means  of  a  brass  plug  inserted  between  a  disc  arid  a  strip 
the  first,  second,  or  third  potential  of  current  may  be  placed  to  the 
line  as  desired. 

The  second  machine  B  supplies  the  first  potential  of  about  70 
volts,  which  is  conducted  to  the  brass  supports  of  the  resistance 
coils  R,  and  thence  to  the  switch,  as  shown. 

The  third  machine  C  also  supplies  an  electro-motive  force  of  70 
volts,  which  being  reinforced  by  the  70  volts  generated  by  j5,  raises 
the  net  potential  to  140  volts,  which  is  conducted  to  the  switch  as 
the  second  potential.  In  like  manner  the  fourth  machine  D  sup- 
plies another  70  volts.  This  being  added  to  the  electro-motive  force 
of  B  and  (7,  increases  the  ^otential  to  210  volts,  which  is  also  con- 
ducted to  the  switch  as  before,  excepting  where  it  is  used  to  supply 
a  quadruplex  or  duplex  circuit,  when  it  is  conducted  directly  to  the 
instruments,  after  passing  through  special  resistance  coils. 

The  last  machine  E  also  generates  an  electro-motive  force  of  70 
volts,  thereby  increasing  the  total  electro-motive  force  of  the  series 
approximately  to  280  volts  potential.  As  previously  stated,  this 
fourth  grade  is  used  only  for  the  longest  quadruplex  and  duplex 
circuits.  Some  of  the  machines  have  fewer  convolutions  on  the 
armatures  than  others,  but  these  are  run  faster  to  compensate. 
The  internal  resistance  of  each  of  these  machines  is  about  I  of  an 
ohm. 

The  quantity  of  current  generated  by  these  machines  would 
appear  to  be  almost  limitless.  Already  over  300  wires  of  an  aver- 


THE  QUADRUPLEX.  59 

age  resistance  of  about  3,000  ohms  are  supplied  from  the  first  po- 
tential without  any  perceptible  diminution  of  the  current  or  appre- 
ciable effect  on  the  working  of  the  machine,  hence  the  great  economy 
of  the  system,  of  which  Mr.  Stephen  D.  Field  is  the  inventor. 

I  have  said  that  upon  the  introduction  of  these  dynamo  machines 
into  the  Western  Union  building  it  was  necessary  to  alter  some- 
what the  connections  and  arrangements  of  the  quadruplex,  etc. 
This  was  owing  to  the  fact,  that  as  the  dynamo  machines  are  run  in 
two  series,  one  supplying  positive  and  the  other  negative  polarity, 
it  is  impracticable  to  tap  a  series  at  each  end  for  change  of  polarity, 
as  in  the  gravity  batteries ;  and  as  each  machine  of  a  series  furnishes 
a  certain  electro-motive  force,  about  70  volts,  it  was  likewise 
impossible  to  regulate  the  small  and  long  ends  of  the  battery  at 
will,  as  is  done  with  the  gravity  cells.  These  difficulties  were  over- 
come :  firstly,  by  changing  the  connections  of  the  pole  changer  so 
that  at  every  alternate  motion  of  its  lever  it  drew  from  first  one 
series  of  dynamos,  and  then  another,  thus  obtaining  the  necessary 
changes  of  polarity ;  and,  secondly,  by  connecting  the  transmitter 
so  that  in  one  position  of  its  lever  it  allows  the  full  current  to  go 
to  the  line  ;  while  in  the  other  the  current  is  forced  to  pass  through 
an  added  resistance  before  reaching  the  line,  and  is  also  given  an- 
other and  generally  a  shorter  route  to  the  earth,  in  the  manner 
hereafter  explained,  so  that  the  current  passing  to  the  line  is  greatly 
weakened. 

The  same  practical  result  is  obtained  by  this  device  as  by  the 
cutting  off  of  a  portion  of  the  battery,  namely,  the  current  on  the 
line  is  increased  or  decreased  at  each  movement  of  the  transmitter. 

In  one  case  the  strength  of  current  is  decreased  by  a  reduction  of 
the  electro-motive  force,  while  in  the  other  case,  as  we  shall  dis- 
cover, the  electro-motive  force  remains  constant,  but  the  circuit 
is  varied. 

The  retractile  spring  of  the  neutral  or  No.  2  relay  is  therefore 
so  adjusted  that  it  withdraws  the  armature  from  the  magnet  when 
the  combination  of  the  added  resistance  and  the  extra  route  to  the 
ground  is  in  operation,  but  when  this  combination  is  inoperative 


60  THE  Q  UADE  UPLEX. 

the  consequent  increased  strength  of  current  going  to  the  line 
attracts  the  armature  precisely  as  when  in  the  gravity  battery 
system  the  entire  battery  is  placed  to  the  line. 

In  a  former  part  of  this  book  it  has  been  stated  that  the  strength 
of  current  on  any  two  wires  supplied  from  the  same  battery  will 
be  the  same  on  each  wire,  provided  the  resistances  of  the  wires  are 
equal.  This  is  equally  true  if  twenty  or  more  wires  of  equal  resist- 
ance are  attached  to  the  same  battery,  and  is  in  accordance  with 
the  following  law  of  electricity  : 

"  The  relative  strengths  of  current  in  the  branches  of  a  divided  cir- 
cuit will  be  inversely  proportional  to  their  resistances"  For  example, 
if  we  have  a  circuit  divided  into,  say,  two  branches,  the  resistance  of 
one  being  12  ohms  and  the  other  6  ohms,  twice  as  much  of  the  cur- 
rent will  flow  through  the  branch  of  6  ohms  as  through  the  one  of 
12  ohms,  because  the  latter  route  offers  double  the  resistance  to  the 
current.  Hence  the  route  offering  6  ohms  resistance  will  carry,  in 
this  case,  two-thirds  of  the  current,  and  the  other  route  one-third. 
But  there  will  not  be  as  much  total  resistance  offered  to  the  current 
by  the  two  routes  together — that  is  to  say,  by  their  joint  resistance 
— as  by  either  route  alone. 

By  joint  resistance  is  meant  the  total  resistance  offered  to  a  cur- 
rent supplied  from  one  battery.  For  example,  if  two  wires  of  6 
ohms  each  are  led  from  one  battery,  the  joint  resistance  of  the  two 
wires  will  be  3  ohms.  Three  wires  of  6  ohms  each  will  have  a  joint 
resistance  of  2  ohms,  etc. 

This  may  be  explained  as  follows :  If  we  have  a  barrel  filled 
with  water  and  attach  one  faucet  at  the  bottom  a  certain  amount 
of  resistance  will  be  offered  to  the  flow  of  water,  another  faucet 
will  decrease  this  resistance,  and  still  another  faucet  by  providing 
an  additional  channel  will  yet  further  reduce  the  resistance. 

The  following  is  a  simple  rule  for  finding  the  joint  resistance  of 
wires  in  a  circuit.  Divide  the  product  of  the  resistances  of  the  two 
wires  by  their  sum. 

If  there  are  more  than  two  wires  in  the  circuit,  first  find  the  joint 
resistance  of  any  two  of  the  wires.  Then  use  this  joint  resistance 


THE  QUADRUPLEX. 


61 


of  the  two  wires  as  though  it  were  the  resistance  of  a  single  wire, 
and  divide  the  product  of  said  joint  resistance  and  the  resistance  of 
the  third  wire  by  the  sum  of  the  same,  which  will  give  the  joint  re- 
sistance of  the  three  wires.  The  joint  resistance  of  the  three  wires 
may  now  be  used  to  find  the  joint  resistance  of  a  fourth  wire,  and 
so  on  indefinitely. 

The  strength  of  a  current  of  electricity,  which  is  the  amount  of 

1  electricity  flowing  through  a  circuit  in  a  given  time,  is  equal  to  the 

number  of  volts  of  electro-motive  force  divided  by  the  number  of 

ohms  of  resistance  in  the  entire  circuit.     This  is  in  effect  Ohm's 

law,  viz.  : 

Electro-motive  force,       ~      E 
Current  =  —  or  (J  =^fr 

Resistance  H 

All  of  these  laws  are  availed  of  in  the  operation  of  the  quadru- 
plex  when  the  currents  from  the  dynamo  machines  are  used. 
Hence  the  necessity  of  a  full  understanding  of  them  before  pro- 
ceeding to  explain  the  latter  system. 


Fig.  32. 

A  preliminary  example  will  now  be  given  of  the  law  of  joint 
resistance,  the  law  relating  to  the  strength  of  currents  in  divided 
circuits,  and  Ohm's  law. 

In  Fig.  32  let  us  suppose  that  up  to  the  point  Jf,  there  is  a  resist- 
ance of  6  ohms.  At  X  the  circuit  divides  into  two  branches,  A 


62 


THE  QITADRUPLEX. 


and  J5,  each  having  36  ohms  resistance.  By  the  rule  given  above, 
we  find  the  joint  resistance  of  these  two  branches,  A  and  J5,  to  be 
18  ohms,  which  added  to  the  6  ohms  resistance  up  to  the  point  X 
makes  the  total  resistance  of  the  circuit  24  ohms.  Supposing  the 
electro-motive  force  to  be  24  volts  (a  vplt  being  the  unit  of  electro- 
motive force),  we  find  that  as  the  strength  of  current  on  a  circuit 
is  equal  to  the  electro-motive  force  divided  by  the  total  resistance, 
in  this  case  it  will  be  §f  =  1.  Up  to  the  point  Jf,  therefore,  the 
strength  of  current  on  the  wire  is  1,  but  at  this  point  the  current 
divides  equally  between  A  and  B,  consequently  on  each  of  these 
branches  the  strength  of  current  will  be  £.  Now  let  us  suppose 
that  this  strength  is  quite  sufficient  to  magnetize  strongly  a  relay 
at  the  distant  end  of  A  or  B,  and  that  in  consequence  its  armature 
has  been  drawn  to  the  cores  of  the  magnet,  as  is  the  case,  for  in- 
stance, when  the  full  battery  is  to  the  line  in  the  Stearns  duplex. 

Now  referring  to  Fig.  33. 

We  have  interposed  an  additional  resistance  of  12  ohms  before 
the  point  X,  and  have  inserted  into  the  circuit  at  that  point  another 


Fig.  33. 

branch,  (7,  having  a  resistance  of  only  9  ohms.  In  this  case  there 
are  18  ohms  resistance  before  X.  Now  we  require  to  find  the  joint 
resistance  of  A,  B,  and  C.  We  have  seen  that  the  joint  resistance 


THE  QUADRUPLEX. 


63 


of  A  and  B  is  18  ohms,  therefore,  by  the  rule  already  quoted,  when 
we  find  the  joint  resistance  of  18  ohms  and  9  ohms,  which  is  6 
ohms,  we  have  the  joint  resistance  of  the  branches  A,  B,  and  0. 
These  6  ohms  added  to  the  18  ohms  inserted  before  X  make  a  total 
resistance  for  this  circuit  of  24  ohms,  the  same  as  in  Fig.  32  The 
strength  of  current,  therefore,  on  this  circuit  up  to  X  is  also  1 ;  but 
now  this  current  has  to  be  divided  proportionately  between  A,  B, 
and  C.  Hence,  as  the  branch  C  offers  only  9  ohms  resistance  while 
the  joint  resistance  of  A  and  B  is  18  ohms,  C  will  receive  twice  as 
much  as  both  A  and  B.  C  will  thus  take  two-thirds  of  the  current, 
while  one-third  remains  to  be  divided  between  A  and  B.  This  gives 
each  of  these  branches  a  current  of  one-sixth,  or  only  one-third 
of  what  it  was  in  Fig.  31,  which  we  will  assume  so  weakens  the 
magnetism  of  the  relay  at  the  distant  end  of  A  that  the  retractile 
spring  withdraws  the  armature. 


Fig.  34. 

Now  if  we  can  arrange  our  connections  so  that  at  one  position  of 
the  transmitter  the  circuit  is  virtually  as  shown  in  Fig.  32  while  in 
the  other  position  the  circuit  is  as  seen  in  Fig.  33,  it  is  evident  that 
we  have  the  necessary  arrangements  for  the  increase  and  decrease 
side  of  the  quadruplex.  In  other  words,  we  may  accomplish  in 


64 


THE  qUADRUPLEX. 


this  way  what  we  performed  previously  by  cutting  off  a  portion  of 
the  battery,  as  already  explained ;  and  this  is,  in  fact,  the  principle 
on  which  the  dynamo  currents  are  used  in  the  quadruplex  system. 

Fig.  34  will  show  the  manner  in  which  these  connections  are 
made.  In  the  present  position  of  the  transmitter  in  that  figure  the 
current  flows  to  the  post  of  the  transmitter,  thence  to  the  tongue 
of  that  instrument,  and  after  passing  through  the  relays  (not  shown 
in  this  figure)  to  the  line  and  rheostat.  It  will  be  seen  that  in  this 
position  of  the  transmitter  there  is  also  another  route  of  1,200  ohms 
resistance,  but,  as  the  present  route  via  the  transmitter  offers  prac- 
tically no  resistance,  all  the  current  will  pass  to  the  line  by  the 
latter  route,  where  it  divides  equally  between  the  two  branches  as 
described  in  Fig.  32. 

When  the  transmitter  is  open,  as  in  Fig.  35,  the  current  neces- 
sarily flows  through  the  600  ohms  at  battery  (which  are  inserted  to 


Fig.  35. 

diminish  the  intensity  of  the  dynamo  currents,  as  mentioned  in  the 
description  of  the  dynamo  machines),  and  the  1,200  ohms  added 
resistance,  to  the  point  JT,  where  it  divides  as  explained  in  Fig.  33, 
two  parts  of  the  entire  current  going  to  the  ground  via  the  trans- 
mitter and  the  900  ohms  resistance,  (which  is  technically  termed 


THE  QUADRUPLEX.  65 

the  "  leak,")  and  one  part  dividing  between  the  line  and  the  rheostat 
branches. 

Since  we  know  that  by  adding  more  resistance  to  a  circuit  having 
a  stated  electro-motive  force  we  can  reduce  the  strength  of  current 
on  the  circuit,  the  question  may  arise  in  the  mind  of  the  reader, 
why  not  simply  arrange  the  connections  so  that  when  the  trans- 
mitter is  closed  the  added  resistance  should  be  out  of  the  circuit, 
and  when  the  transmitter  is  open  the  added  resistance  should  be 
included  in  the  circuit,  thus  dispensing  with  the  third  branch  C  or 
"  leak  "  ?  The  reason  is,  briefly,  that  the  introduction  of  resistance 
for  the  reduction  of  the  strength  of  current  has  been  found  to 
operate  unsatisfactorily  on  quadruplex  circuits ;  which  is  mainly 
owing  to  the  fact,  that  so  much  resistance  must  be  inserted  in  the 
circuit  to  cause  the  instruments  affected  by  the  increase  and  de- 
crease of  strength,  to  act  quickly,  that  it  has  a  detrimental  effect 
upon  the  instruments  worked  by  the  changes  of  polarity. 

The  problem,  therefore,  to  be  solved  was,  how  to  arrange  the  con- 
nections for  the  dynamo  machine  currents,  so  that  whether  the 
transmitters  were  open  or  closed  the  resistance  of  the  line  should 
be  the  same,  and  the  problem  was  finally  solved  by  the  ingenious 
addition  of  the  leak  in  combination  with  the  added  resistance. 

That  this  is  so  we  may  see  by  referring  to  Fig.  34  and  following 
out  the  routes. 

A  current  coming  from  A,  in  the  position  of  the  transmitter  in 
this  figure,  would  encounter,  after  passing  the  point  X,  600  ohms, 
not  counting  the  1,200  ohms  added  resistance.  In  Fig.  35,  after 
passing  point  X  there  is  now  a  choice  of  two  routes,  namely,  one 
via  the  1,200  ohms  added  resistance  and  the  600  ohms  at  the  ma- 
chine (making  1,800  ohms),  and  the  other  via  the  transmitter  and 
through  the  leak  of  900  ohms.  We  know  that  the  joint  resistance 
of  1,800  and  900  ohms  is  600 ;  thus  the  total  resistance  from  the 
point  Xto  the  various  grounds  at  the  home  end  remains  the  same 
in  either  position  of  the  transmitter,  while,  as  we  have  seen,  the 
strength  of  current  reaching  the  distant  end  A  or  B  is  materially 
altered  at  each  change  in  the  position  of  that  instrument.  Let  the 


63  THE  QUADRUPLEX. 

reader  bear  in  mind,  therefore,  that,  notwithstanding  the  insertion 
and  practical  removal  of  these  various  resistances  from  the  line,  the 
actual  total  resistance  of  the  quadruplex  circuit  is  not  changed.  It 
is  the  insertion  of  the  branch  circuit,  or  leak  to  ground,  that  is  the 
prime  factor  in  obtaining  the  desired  increase  and  decrease  of 
strength. 

In  applying  machine  currents  to  the  quadruplex,  almost  the  same 
instruments  as  are  used  with  a  gravity  battery  will  answer  on  short 
lines,  where  comparatively  weak  currents  are  used,  but,  where  con- 
siderable strength  of  current  is  required,  the  spark  produced  at  the 
contact  points  of  the  ordinary  continuity  preserving  pole  changer, 
at  the  moment  of  reversal  of  polarity,  is  sufficient  to  interfere  with 
its  satisfactory  working. 

For  this  reason  a  pole  changer,  such  as  is  shown  in  Fig.  36,  is 
used  on  long  quadruplex  circuits. 

Its  construction  is  very  simple.  The  straight  lever  L  is  pivoted 
on  the  standards  S,  so  that  when  either  of  the  ends  of  the  lever 
is  depressed,  it  will  come  in  contact  with  the  upright  post  Z  or  C 
beneath  it.  The  ends  of  the  lever  and  the  tops  of  these  posts  are 
furnished  with  platina  contact  points.  The  posts  are  insulated  from 
the  plate  upon  which  they  stand.  The  retractile  spring  is  also 
insulated  from  the  hook  at  the  point  P  to  prevent  short  circuiting. 
The,  line  is  connected  to  the  lever  via  the  standards  S,  and  the  two 
posts  Z  and  (7  are  connected,  one  to  a  positive  series  of  dynamo 
machines  and  the  other  to  a  negative  series.  It  may  thus  be  seen 
that  if  the  right  hand  end  be  depressed,  making  contact  at  C,  con- 
tact will  be  broken  at  Z  and  a  positive  current  will  flow  to  the 
line. 

With  the  left  hand  end  depressed,  contact  will  be  made  at  Z, 
and  the  polarity  will  be  reversed. 

It  will  be  noticed  that,  with  this  style  of  pole  changer,  contact  is 
not  made  with  one  post  until  after  the  other  has  broken  contact, 
and  thus  short  circuiting  of  the  battery  is  entirely  obviated. 

The  figures  which  I  have  heretofore  quoted,  showing  the 
amount  of  resistance  placed  in  the  "  added  resistance "  as  1,200 


THE  QUADRUPLEX. 


67 


ohms,  and  that  in  the  "  leak  "  as  900  ohms,  give,  as  we  have  seen, 
a  difference  equal  to  3  to  1,  in  the  strength  of  current  which  reaches 
the  distant  station,  in  the  different  positions  of  the  transmitter. 

This  margin  is  found  sufficient  on  circuits  of  medium  length,  but 
on  very  long  circuits  better  results  are  obtained  when  the  margin 


Fig.  36. 

is  made  greater,  for  instance,  4  to  1.  With  a  gravity  battery  the 
division  of  the  electro-motive  force  necessary  to  obtain  this  margin 
is  easily  made  by  apportioning  the  "  long  "  and  "  short "  ends  of. 
the  battery,  respectively,  the  requisite  number  of  cells  to  produce 
the  desired  result. 

Thus  in  a  battery  of  300  cells,  the  "  short  end  "  would  be  appor- 


68  THE  qUADRUPLEX. 

tioned  75  cells  to  obtain  this  margin.  But,  as  I  have  previously 
stated,  it  is  not  practicable  to  alter  thus  the  electro-motive  force 
furnished  by  the  dynamo  machines ;  therefore,  when  it  is  desired  to 
increase  the  margin  as  above,  namely,  to  make  'the  ratio  as  4  to  1, 
the  resistance  in  the  leak  is  made  still  lower  (thus  enabling  it  to 
carry  a  greater  portion  of  the  current  away  from  the  line),  and  at 
the  same  time  the  "added  resistance  "  is  increased.  Of  course  these 
resistances  must  be  so  chosen  that  whether  the  transmitter  is  open 
or  closed  the  total  resistance  of  the  line  will  be  the  same. 

In  actual  practice  the  figures  adopted  for  obtaining  the  ratio  of 
4  to  1  are,  for  the  "leak,"  800  ohms,  and  for  the  "  added  resistance," 
1,800  ohms.  It  will  be  found  that  the  joint  resistance  of  2,400 
ohms  (viz. :  the  600  ohms  at  the  machines  and  the  1,800  ohms 
"  added  resistance  ")  and  the  resistance  of  the  "  leak,"  800  ohms,  is 
600  ohms. 

Since  it  is  desirable  to  have  the  variable  resistances  under  con- 
venient control  in  order  to  work  lines  of  any  length  or  resistance 
upon  the  same  set  of  instruments,  the  added  resistance  and  leak 
resistance  are  usually  placed  in  the  same  box,  as  shown  in  Fig  37. 


Fig.  37. 

The  leak  consists  of  two  resistance  coils  of  100  and  800  ohms, 
respectively,  arranged  in  such  a  manner  that  by  inserting  a  metallic 
plug  at  L  the  100  ohm  coil  may  be  cut  out.  The  added  resistance 
coils  measure  600  and  1,200  ohms,  respectively,  arranged  so  that 
the  600  ohm  coil  may  be  cut  out  by  a  plug  inserted  at  R.  Thus 


THE  QUADRUPLEX. 


69 


the  leak  may  be  readily  changed  from  800  to  900  ohms,  and  the 
added  resistance  from  1,200  to  1,800  ohms. 

When  machine  currents  are  used  it  is  convenient  to  have  some 
means  of  quickly  opening  the  circuits  between  the  machines  and 
the  home  instruments,  not  only  to  facilitate  any  repairs  or  altera^ 
tions  that  may  require  to  be  made,  but  also  to  cut  out  the  instru- 
ments in  case  of  short  circuiting  of  the  wires  at  any  point.  For 
this  purpose  each  quadruplex  set  is  furnished  with  a  switch  similar 
to  the  one  shown  in  Fig.  38.  The  brass  strips  B  and  E"  are  con- 
nected at  their  top  ends  directly  with  the  dynamo  machines,  as  may 


be  seen  in  Fig.  40,  while  the  strip  B'  is  connected  to  the  line.  The 
lower  ends  of  B  and  B"  are  led  to  the  posts  of  the  pole  changer. 
By  moving  B  and  B"  to  the  right  they  are  placed  on  the  dead 
points,  Z>,  Z>',  and  of  course  the  machine  currents  are  thus  taken  off 
the  instruments.  By  placing  the  strip  B'  on  the  point  6r,  the  line 
is  placed  to  the  ground  through  a  resistance  equal  to  the  resistance 
of  600  ohms  at  the  machines.  The  dotted  lines  represent  the  con- 
nections between  the  buttons  under  the  wood  of  the  switch. 

Fig.  39  is  a  diagram  of  the  quadruplex  arranged  to  be  operated 
at  station  A  by  dynamo  machine  currents,  and  at  B  by  the  usual 
gravity  battery  currents.  It  will  be  seen  that  the  latter's  connec- 


70 


THE  QUADRUPLEX. 


THE  qiTADRUPLEX. 


71 


72  THE  QUADRUPLEX. 

tions  remain  exactly  the  same  as  when  both  ends  of  the  circuit  are 
supplied  by  gravity  batteries. 

There  is  no  necessity  for  a  further  explanation  of  the  operation 
of  this  arrangement,  as  the  effects  produced  are  precisely  analogous 
to  those  already  stated  in  the  description  of  the  regular  quadruplex. 

In  Fig.  40  may  be  seen  the  actual  connections  required  by  the 
arrangement  under  consideration,  the  only  parts  omitted  being 
the  local  sounder  of  the  polarized  relay  and  the  resistances  that  are 
interposed  between  the  dynamo  machines  and  the  switch  S. 

Each  instrument  is  plainly  indicated  by  its  name. 

It  only  remains,  therefore,  to  point  out  the  route  of  the  current 
in  the  different  positions  of  the  transmitter,  and  these  are  located 
by  consecutive  figures  and  letters  in  the  diagram.  For  instance, 
when  the  transmitter  is  closed,  as  in  the  diagram,  the  route  is 
shown  from  the  dynamos  by  figures  1  up  to  8,  where  the  current 
splits,  as  heretofore  explained. 

When  the  transmitter  is  open,  the  current  divides  at  A,  and  that 
portion  which  proceeds  to  the  line  passes  through  the  added  resist- 
ance to  5,  thence  to  D,  where  it  again  splits,  as  in  the  former  case. 
That  portion  of  the  current  which  seeks  a  ground  through  the  leak 
passes  from  A  to  the  tongue  of  the  lever,  thence  to  (?'  and  to  the 
ground. 


IX. 


THE  PRACTICAL  WORKING  OF  THE  QUADRUPLEX. 


BY    WM.    HAVER,    JR. 


After  first-class  instruments,  perfect  connections,  and  well  kept 
batteries,  nothing  conduces  so  much  to  the  successful  working  of 
the  quadruplex  as  intelligent  handling. 

By  intelligent  handling,  1  mean  that  the  persons  in  charge  of  a 
quadruplex  set  or  sets  should  have  a  thorough  theoretical  and  prac- 
tical knowledge  of  the  entire  system.  The  theory  may  be  mastered 
by  study,  but  the  practical  knowledge  can,  as  a  rule,  only  be  gained 
by  experience. 

It  is  not,  however,  always  practicable  to  have  an  experienced 
person  in  charge  of  a  system,  for  it  frequently  happens  that  a  quad- 
ruplex circuit  is  installed  in  an  office  and  placed  under  the  care  of  a 
manager  or  chief  operator  who  may  never  have  seen  a  quadruplex 
set  before. 

An  enterprising  manager,  in  such  a  case,  will,  of  course,  at  once 
endeavor  to  post  himself  in  all  the  details  of  the  system,  but  these 
are  more  numerous  than  some  people  suppose,  and  while  the  man- 
ager is  acquiring  his  knowledge  the  best  results  cannot  be  expected 
from  that  particular  quadruplex  system. 

In  the  hope  that  my  experience  may  be  of  service  to  this  class  in 
the  management  of  their  quadruplex,  as  well  as  to  others  who  may 
wish  information  on  this  subject,  I  propose  to  jot  down  as  many  ot 
the  causes  of  trouble,  and  the  symptoms  occasioned  by  certain  kinds 
•of  trouble,  as  I  can  recall,  together  with  any  hints  as  to  the  manner 
of  obtaining  the  best  results  from  the  system,  that  may  occur  to  me. 

The  following  are  some  of  the  technical  terms  and  expressions 
-used  in  speaking  of  the  quadruplex  and  its  connections  : 

The  "  tap  "  or  "  tap  wire  "  is  that  wire  which  taps  the  battery  and 


74  THE  QUADRUPLEX. 

is  led  to  the  bar  of  the  transmitter.  It  may  be  seen  at  point  Z  in 
Fig.  28.  The  "short  end"  of  the  battery  is  that  portion  between 
the  ground  and  Z  in  the  same  figure.  The  short  end  is  generally 
to  the  line  when  the  transmitter  is  open.  The  "  long  end  "  of  the 
battery  refers  to  the  portion  between  the  points  P  and  F,  also  in 
the  same  figure.  This  is  referred  to  chiefly  when  there  is  apparent 
trouble  in  that  portion  of  the  battery,  as  explained  hereafter.  To 
"  reverse  "  means  to  open  and  close  the  pole  changer,  which  instru- 
ment, as  is  well  known,  reverses  the  battery  at  each  motion. 

The  "  ground  coil "  is  that  resistance  which  is  placed  between 
the  three  point  switch  B  in  Fig.  30,  and  the  ground,  to  compensate 
for  the  internal  resistance  of  the  entire  battery.  It  is  sometimes 
called  the  "spark  coil." 

The  "  polar  relay "  is  the  No.  1  relay.  The  "  neutral  relay  "  is 
the  No.  2  relay. 

To  "  dot "  or  "  write  on  both  sides "  is  to  write  on  the  pole 
changer  and  transmitter  simultaneously. 

Care  should  be  taken  that  the  compensating  battery  resistances, 
such  as  that  between  the  tap  of  the  battery  and  the  bar  of  the 
transmitter,  are  correct. 

It  may  be  assumed  that  two  and  one-half  ohms  per  cell  is  the 
average  internal  resistance  of  a  battery  cell. 

On  circuits  of,  say  100  miles,  it  is  common  to  divide  the  battery 
into  two  equal  portions,  namely,  (supposing  that  there  are  100  cells 
in  the  battery,)  of  fifty  cells  each. 

Thus  when  the  transmitter  is  open  fifty  cells  are  placed  to  the 
line,  and  when  it  is  closed,  100  cells.  This  is  called  giving  a  margin 
of  two  to  one. 

On  longer  circuits  the  margin  is  made  wider,  until  on  some  cir- 
cuits, such  for  example  as  that  between  Bangor,  Me.,  and  New  York, 
it  is  four  to  one,  that  is  to  say,  (supposing  that  there  are  in  all  400 
cells  of  battery,)  there  would  be  100  cells  to  the  line  when  the 
transmitter  is  open,  and  400  when  closed. 

This  increase  of  the  margin  is  rendered  necessary  by  the  fact 
that  on  long  lines  there  is  considerable  retardation  and  prolongation 


THE  qUADRITPLEX.  75 

of  a  current,  and  it  is  thus  essential  that  the  difference  of  potential 
between  the  entire  battery  and  the  "  short  end  "  of  it  should  be 
greater,  so  that  the  variations  in  the  amount  of  current  reaching 
the  distant  neutral  relay  may  be  more  marked. 

The  method  of  balancing  a  quadruplex  has  already  been  ex- 
plained in  the  foregoing  chapters,  but  it  is  a  subject  which  I  am  sure 
will  bear  amplification. 

As  already  stated,  the  distant  station,  which  for  the  sake  of  brevity 
I  shall  frequently  hereafter  call  -Z?,  is  first  requested  to  "ground." 
Having  done  so,  he  should  avail  himself  of  the  opportunity  to  see 
that  the  number  of  ohms  resistance  in  his  "  ground  coil "  is  correct. 
The  ground  coil  is  that  resistance  which  is  interposed  between  the 
line  and  the  ground,  when  one  "  grounds."  As  previously  men- 
tioned, the  ground  coil  is  put  in  to  compensate  for  the  "  internal " 
resistance  of  your  battery.  It  very  often  happens  that  an  inexperi- 
enced "balancer"  will  unwittingly  alter  this  resistance,  to  the  seri- 
ous detriment  of  your  balance.  For  instance,  if  the  internal  resist- 
ance of  a  battery  is  600  ohms,  and  by  inadvertence  1,200  has  been 
inserted,  it  will  divert  an  unequal  portion  of  your  battery  current 
to  the  line,  and  thus  render  your  balance  unsteady.  Of  course  it  is 
equally  necessary  that  you  should  examine  your  own  ground  coil. 

When  B  has  grounded,  you  also  ground. 

The  next  thing  to  be  done  is  to  place  the  armature  of  your  polar 
or  No.  1  relay  in  the  "center,"  that  is,  so  to  adjust  it  that  it  will 
remain  on  whichever  side  it  is  placed.  You  then  "  cut  in  "  your 
battery  and  change  the  resistance  in  your  rheostat  until  the  lever 
again  remains  where  it  is  placed. 

Sometimes  it  happens  that,  owing  to  heavy  inductive  effects  on 
the  wire,  it  is  impossible  to  find  this  center,  the  armature  keeping 
up  a  constant  clatter.  In  this  case  you  must  use  your  judgment 
and  adjust  the  armature  in  that  position  where  the  attraction  to 
either  pole  of  the  relay  is  about  even.  You  then,  as  before,  place 
your  battery  to  the  line.  If  the  wire  is  much  out  of  balance,  the 
armature  of  the  polar  relay  will  now  be  strongly  attracted  to  one 
side,  in  that  case,  alter  the  rheostat  resistance  again.  As  you  ap- 


76  THE  qUADRUPLEX. 

proach  the  balance,  the  inductive  effects  of  the  line  will  again  begin 
to  be  felt,  and  again  your  judgment  must  be  exercised  as  to  when 
you  have  a  nearly  perfect  balance.  When  this  is  obtained,  request 
the  distant  station  to  "  cut  in  "  his  battery ;  when  he  does  so  you 
will  very  likely  find  that  the  inductive  effects  have  disappeared, 
having  now  been  overcome  by  the  distant  station's  battery. 

On  wires  not  exceeding  from  70  to  100  miles  the  static  discharge 
from  the  line  is  scarcely  sufficient  to  interfere  with  the  working  of 
Morse  circuits,  therefore,  on  such  wires  condensers  are  unnecessary. 

A  few  words  more,  here,  explanatory  of  the  static  discharge  or 
return  current,  may  be  of  use  to  the  beginner. 

To  illustrate,  let  us  suppose  that  we  have  a  pipe  between  any  two 
points,  somewhat  remote,  and  let  us  further  suppose  that  we  have 
at  one  end  of  this  pipe  an  engine  pumping  water  through  it.  Also 
let  us  suppose  that  we  have  at  each  end  of  the  pipe  a  wheel,  which 
will  be  revolved  in  a  certain'direction  accordingly  as  the  water  flows. 
Now  if  we  suddenly  stop  the  pumping  engine,  leaving  at  the  same 
moment  both  ends  of  the  pipe  open,  it  is  quite  evident  that  the 
water  in  the  pipe  will  empty  itself  at  both  ends,  and  the  water  at 
the  end  where  we  had  supposed  the  engine  to  be  will  run  out  in  an 
opposite  direction  to  that  in  which  it  had  been  flowing  into  the 
pipe,  and  if  there  is  enough  water  so  left  in  the  pipe,  as  there 
probably  will  be  if  the  pipe  is  sufficiently  long,  this  returning  water 
will  reverse  the  direction  of  the  wheel. 

If  we  could  imagine  that  the  sides  of  this  pipe  were  of  a  spongy 
nature,  it  would  be  easy  to  believe  that  the  capacity  of  the  pipe  for 
holding  water  would  be  increased,  and,  consequently,  the  greater 
would  be  the  outflow  of  the  return  current  when  we  should  sud- 
denly stop  the  engine,  and  the  greater  would  be  the  effect  of  this 
outflow  upon  the  wheel. 

Now  the  foregoing  action  of  water  in  a  pipe  is  partly  analogous 
to  the  action  that  takes  place  in  a  telegraph  wire.  The  battery 
supplies  the  electric  current  on  the  wire.  The  action  of  induction, 
previously  explained  under  the  heading  of  condensers,  gives  to  the 
wire  a  greater  capacity  for  retaining  electricity.  The  pole  changer 


THE  QUADRUPLEX.  77 

momentarily  cuts  off  this  supply  of  electricity.  The  electricity  left 
in  the  wire  at  that  moment  seeks  to  return  to  the  earth,  and  in 
doing  so  temporarily  charges  the  relay,  giving  a  short  false  signal. 

The  condenser  obviates  this  trouble  in  the  manner  already  ex- 
plained. It  should  be  stated  that  the  coils  in  the  rheostat  which 
form  the  artificial  wire  have  a  very  small  capacity  for  retaining 
electricity,  and  hence,  although  they  offer,  when  properly  adjusted, 
as  much  resistance  to  the  electric  current  as  the  main  line,  do  not, 
at  the  moment  when  the  battery  is  cut  off,  send  back  anything  like 
so  large  a  return  'current. 

The  condenser  being  placed  in  the  artificial  line,  as  shown  in  the 
diagrams,  when  rightly  adjusted  gives  that  wire  an  artificial  capacity 
equal  to  that  of  the  main  line,  and  as  the  condenser  discharges  at 
the  same  moment  as  the  main  line,  but  goes  around  the  core  in  an  op- 
posite direction  to  the  line  discharge,  the  home  relay  is  not  affected. 

After  having  balanced  the  quadruplex,  it  now  remains  to  adjust  the 
condenser  so  that  it  shall  give  a  discharge  equal  to  that  from  the 
line.  This  requires  a  greater  degree  of  skill  than  simply  to  balance 
a  quadruplex  and  almost  every  expert  has  his  own  way  of  proceeding. 
I  have  found  that  I  could  always  eliminate  the  static  effects  by  simply 
closing  the  No.  2  key,  (so  that  the  full  battery  will  be  to  the  line,) 
and  dotting  on  the  pole  changer,  in  the  meantime  adjusting  the 
condenser,  by  taking  out  or  putting  in  plugs,  until  the  motion  of 
the  polar  relay  in  response  to  my  pole  changer  was  reduced  to  a 
sort  of  a  light  double  click. 

So  long  as  the  polar  relay  responds  clearly  to  each  motion  of  your 
pole  changer,  the  static  balance  may  be  considered  imperfect. 

Another  method  for  adjusting  the  condenser  is,  after  balancing,  to 
give  the  adjusting  screw  of  the  polar  relay  a  bias  to  one  side  or  the 
other  until  a  well  defined  click  is  heard,  then  to  insert  or  remove 
plugs  in  the  condenser  (at  the  same  time  bringing  back  the  arma- 
ture of  the  polar  relay  to  its  former  position)  until  this  click  is 
eliminated. 

I  consider  that  this  method  has  a  defect,  especially  in  the  hands 
of  beginners,  as  it  alters  the  "  center  "  of  the  polar  relay  armature 


78  THE  QVADRVPLEX. 

and  may  thus  interfere  with  the  satisfactory  working  of  the  polar 
side. 

Another  method,  and  a  very  good  one  I  think,  is,  after  balancing, 
to  request  B  to  put  his  battery  on,  and  to  so  place  his  key  that  your 
polar  relay  armature  rests  on  the  local  contact  point.  See  that 
your  own  full  battery  is  also  to  the  line.  Now  dot  on  your  pole 
changer  and  adjust  your  condenser  until  it  has  no  effect  whatever 
on  your  polar  relay's  armature.  If  the  static  discharge  has  no  effect 
on  your  polar  relay  under  the  above  circumstances,  it  will  not  be 
likely  to  effect  it  under  any  other  circumstances. 

The  reason  I  advise  noticing  that  your  full  battery  is  to  the  line, 
when  you  are  adjusting  for  "  static,"  is,  that  the  static  discharge 
varies  with  the  amount  of  battery  to  the  line.  The  greater  the 
amount  of  battery  to  the  line  the  greater  will  be  the  return  dis- 
charge. 

After  this  has  been  done  and  the  distant  station  has  also  balanced, 
the  following  test  should  be  made  to  ascertain  whether  the  adjust- 
ments are  correct : 

Ask  B  to  dot  on  his  No.  1  side  and  to  write  on  the  No.  2  side. 
Now  listen  to  see  that  B's  writing  on  No.  2  side  is  coming  all  right, 
at  the  same  time  open  and  close  your  own  pole  changer  and  trans- 
mitter. If  you  get  his  writing  clearly  under  these  circumstances, 
which  of  course  is  equivalent  to  having  all  sides  working  at  once, 
your  balance  is  correct. 

The  distant  station  should  then  go  through  the  same  performance. 

If  it  should  transpire  that  while  B  is  writing  on  both  sides  you  do 
not  get  him  clearly  on  No.  2  side,  after  you  have  carefully  adjusted, 
request  him  to  write  on  No.  2  side  only.  If,  while  he  is  so  writing, 
his  pole  changer  should  be  open,  and  you  get  him  O.  K.,  next  ask 
him  to  close  his  pole  changer  and  to  continue  writing  on  No.  2  side. 
If  you  also  get  him  O.  K.  with  pole  changer  closed,  it  would  appeal 
that  the  trouble  is  in  his  pole  changer's  points,  and  in  that  case  an 
examination  of  them  will  probably  reveal  that  the  trouble  was 
caused  by  dirty  points,  or  uneven  contacts. 

When  your  No.  2  side  is  broken  up  by  the  movements  of  B's  pole 


THE  qiTADRUPLEX.  79 

changer,  it  is  technically  said  that  his  "  reversals  "  break  up  or  con- 
fuse No.  2  side. 

A  small  file,  adapted  to  go  under  the  contact  points  of  the  pole 
changer  and  transmitter,  is  a  tool  every  manager  of  a  quadruplex  set 
should  possess. 

If,  after  B  has  cleaned  his  points,  the  trouble  be  not  removed,  try 
your  balance  again  carefully.  This  is  especially  necessary  in  bad 
weather. 

If  you  get  B's  writing  "  light  "  on  either  side,  ask  him  to  clean 
his  points  on  both  sides.  Should  he  complain  that  you  come 
"  light,"  likewise  clean  your  points  "  all  around."  When  the  con- 
tacts become  oxidized  it  is  well  known  that  this  increases  the  re- 
sistance at  the  points  of  contact,  and  consequently  the  strength  of 
current  is  reduced. 

If,  while  B  is  dotting  on  the  pole  changer,  you  are  unable  to  read 
him  on  No.  2  side,  again  get  him  to  write  on  No.  2  side  only,  and 
request  him  to  give  you  one  pole  at  a  time.  This  he  does  by  first 
closing  and  then  opening  his  pole  changer,  as  you  direct.  If  you 
find  that  when  he  closes  his  pole  changer,  for  instance,  you  do  not 
get  him  at  all  on  No.  2  side,  while  you  do  get  him  while  his  pole 
changer  is  open,  it  indicates  that  one  of  the  tongues  of  his  pole 
changer  is  not  making  connection  ;  call  his  attention  to  that  fact. 

If  while  B  is  dotting  on  No.  2  side  you  cannot  get  him  readably  on 
No.  1  side,  likewise  ask  him  to  give  you  his  full  battery  and  his  short 
end  alternately.  This  he  does  by  first  closing  his  transmitter  (giv- 
ing you  all  of  his  battery).  If  now  you  do  not  get  him  on  polar 
side,  next  ask  him  to  give  you  his  short  end,  which  he  does  by  open- 
ing his  transmitter ;  if  now  you  get  him,  it  indicates  that  there  is 
trouble  between  the  "  tap  "  of  his  battery  and  the  post  of  his  trans- 
mitter, probably  a  bad  or  broken  connection  in  battery  ;  or  it  may 
be  that  the  tongue  of  his  transmitter  is  not  making  proper  connec- 
tion with  the  post  of  transmitter. 

Should  the  trouble  be  that  you  do  not  get  him  when  his  trans- 
mitter is  open,  while  you  do  when  it  is  closed,  the  trouble  would 
appear  to  be  that  there  is  either  a  bad  connection  between  where 


80  THE  QUADRUPLEX. 

his  battery  is  tapped  and  the  bar  of  his  transmitter,  or  that  per- 
haps the  tongue  of  the  transmitter  is  not  making  proper  contact 
with  the  bar  of  the  transmitter. 

By  reference  to  the  diagrams  of  the  quadruplex',  Fig.  28,  it  will 
be  seen  to  what  I  allude. 

If  it  happens  when  all  sides  are  working  that  you  do  not  get  B 
well  on  No.  2  side,  notice  carefully  whether  you  do  get  him  all  right 
on  that  side  when  your  No.  1  side  is  quiet.  If  so,  the  trouble,  most 
likely,  is  caused  by  an  imperfect  static  balance  at  your  end.  If  you 
find  you  do  not  get  B  well  on  No.  1  side  when  your  transmitter  is 
closed,  but  that  you  do  when  it  is  open,  this  trouble,  too,  is  proba- 
bly occasioned  by  bad  static  balance. 

If  you  find  that  your  condenser  seems  to  have  no  effect  on 
the  static  discharge,  in  the  way  of  removing  it,  examine  the  con- 
nections of  condenser  ;  it  may  be  that  they  have  become  detached. 
It  is  as  bad  to  have  too  many  of  the  condenser  plates  in  action,  as 
too  few.  Therefore  such  an  occurrence  should  be  avoided. 

It  occasionally  happens  that  when  one  wire  becomes  crossed  with 
another,  one  of  the  wires  is  cleared  by  opening  the  other  at  both 
ends. 

If  the  wire  so  cleared  should  be  a  quadruplex  or  duplex  wire,  the 
effect  on  the  static  discharge  will  be  at  once  noticeable,  namely,  it 
will  be  much  increased.  It  is  in  some  cases  necessary  to  add  another 
condenser  to  offset  this  abnormal  discharge ;  an  additional  amount  of 
resistance  placed  between  the  condensers  and  the  artificial  wire  may 
also  be  thus  rendered  necessary,  as  the  static  discharge  in  this  case 
is  somewhat  more  gradual  than  ordinarily. 

When  a  wire  has  not  been  balanced  since  the  previous  day,  and  if 
in  the  meantime  the  weather  has  considerably  changed,  or  if  there 
has  been  a  decided  change  in  the  weather  at  any  time,  it  may  occur 
that  you  will  not  hear  B  calling  or  answering  your  calls,  the  wire 
being  so  much  out  of  balance.  In  this  case  it  is  a  good  plan  to  call 
B  a  few  times,  and  then  suddenly  ground  your  end.  If  B  is  there, 
and  answers  you,  you  will  be  sure  to  hear  him  now.  If  so,  cut  in 
again,  ask  him  to  ground,  and  proceed  with  your  balance  as  usual. 


THE  QUADRUPLEX.  81 

When  there  has  been  a  change  in  the  weather  from  dry  to  wet,  it 
will  probably  be  necessary  to  lower,  very  considerably,  the  tension 
of  the  spring  of  No  2  relay,  before  you  will  be  able  to  get  B.  This 
is  because  the  margin  of  his  current  reaching  you  has  fallen  in  pro- 
portion to  the  state  of  the  weather,  as  well  as  the  condition  of  the 
wire  insulation. 

On  the  contrary,  if  the  weather  changes  from  wet  to  dry,  it  will 
be  found  necessary  to  increase  the  tension  of  the  No.  2  relay,  the 
margin  from  B  having  increased. 

After  a  balance  has  been  taken  on  the  quadruplex,  it  is,  generally 
speaking,  best  not  to  alter  the  adjustment  of  the  polar  relay  under  any 
circumstances.  I  am  aware  that  some  quadruplex  experts  favor  giv- 
ing the  armature  of  this  instrument  a  bias  to  the  local  contact  point, 
but  I  do  not  think  the  theory  of  the  quadruplex  will  justify  this 
action.  It  should  be  considered  that  the  object  of  placing  the  arma- 
ture in  the  "  center,"  before  balancing,  is  to  make  certain  that  the 
amount  of  current  flowing  through  each  coil  from  the  home  bat- 
tery shall  be  equal ;  and  that  the  quadruplex  is  actually  worked  by 
the  production  of  inequalities  of  the  currents  flowing  through  these 
coils,  and  thus,  that  any  bias  to  one  side,  which  may  be  given  to  the 
lever,  is  equivalent  to  sending  more  current  through  that  side  from 
the  home  battery.  Furthermore,  the  fact  of  the  lever  being  exactly 
in  the  center  is  relied  upon  to  keep  it  perfectly  still  when  the  dis- 
tant battery  is  momentarily  cut  off  during  the  changes  of  polarity 
at  the  distant  station,  for  at  that  instant,  as  we  know,  the  induced 
magnetism  of  the  polar  relay  comes  into  play  and  retains  the  lever 
at  whichever  side  it  may  happen  to  be  at  that  moment.  Conse- 
quently, if  the  lever  is  biased,  it  is  possible  that  should  the  lever 
happen  to  be  on  the  unbiased  side  it  might  tend  to  move  to  the 
other  side  and  thus  make  a  "  click." 

It  is  true  that  if  but  one  side  of  the  quadruplex  is  working,  a 
change  in  the  balance  may  be  tided  over  by  simply  changing  the  ad- 
justment of  the  levers,  but  this  is  only  a  makeshift  at  best.  Should 
writing  from  B  come  light  on  the  polar  side,  the  true  remedy  does 
not  consist  in  biasing  the  armature.  First  ascertain  that  the 


82  THE  QUADRUPLEX. 

trouble  is  not  in  a  weak  local,  dirty  contact  points,  bad  adjustment 
of  sounders,  or  in  your  balance  ;  after  that,  request  the  distant  sta- 
tion to  diminish  the  tension  of  the  spring  on  his  pole  changer. 
If  none  of  these  resorts  obviates  the  trouble,  and  the  batteries  and 
wire  are  all  right,  it  might  be  well  to  try  what  result  would  ensue 
from  a  change  of  the  sending  operator.  It  has  often  been  noticed 
that  some  operators  do  not  seem  to  have  the  correct  method  of 
sending  signals  through  on  duplex  or  quadruplex  circuits. 

Where  a  repeating  sounder  is  used  on  the  No.  2  side,  trouble 
is  sometimes  caused  by  its  contact  points  sticking,  or  becoming 
loose  ;  they  should  be  looked  after. 

In  balancing  you  may  sometimes  find  it  impossible  to  get  "  a 
balance,"  and  that  no  amount  of  changing  of  the  rheostat  resistance 
produces  any  effect  on  the  relay.  This,  however,  does  not  occur 
very  frequently.  It  may  be  owing  to  several  causes.  For  instance, 
the  polar  relay  may  have  become  defective  ;  burned  out,  as  it  is 
called,  by  an  unusually  strong  current,  such  as  lightning,  etc.,  or  the 
rheostat  may  have  failed,  some  of  the  coils  thereof  having  broken, 
perhaps;  or  the  trouble  may  be  in  the  condenser.  This  would 
be  the  case  if  a  ground  plate  should  touch  a  line  plate.  This  may 
be  tested  for  by  temporarily  detaching  the  wire  from  the  condenser. 

The  relay  may  be  tested  by  taking  out  all  the  wires  from  its 
thumb  screws  but  the  battery  wire,  and  by  feeling  with  wet  fingers, 
or  a  piece  of  wire,  to  ascertain  whether  the  current  comes  through  to 
any  of  the  other  thumb  screws  than  the  one  it  naturally  should 
come  to.  The  permanent  magnet  should  also  be  tested  to  ensure 
that  it  is  not  crossed,  by  way  of  the  core  of  the  electro-magnet 
of  the  relay,  with  either  of  the  coils.  It  is  understood,  of  course, 
that  if  the  fingers  are  used  for  this  test,  the  other  hand  must  be 
touching  a  ground  wire,  or  if  a  wire  be  used,  one  end  of  it  must  be 
to  ground.  The  wire  is  the  best,  as  it  will  show,  by  a  spark,  a  lower 
current  than  the  fingers  would  detect. 

The  neutral  relay  may  also  be  affected  and  tested  in  the  same 
way. 

If  the  current  should  be  found  in  other  than  the  thumb  screw 


THE  QUADRUPLEX.  83 

which  is  the  terminus  of  the  coil  attached  to  the  battery  as  above, 
it  shows  the  relay  to  be  defective,  probably  the  coils  are  crossed 
with  each  other. 

Another  source  of  trouble  is  the  crossing  of  a  portion  of  one  coil 
with  another  portion  of  itself,  which  would  make  the  resistance  in 
the  crossed  coil  of  the  relay  much  lower  than  the  uncrossed  one,  as 
the  wire  between  the  crossed  portions  of  the  crossed  coil  would  be 
virtually  cut  out. 

The"  effect  of  such  an  occurrence  is  this  :  Suppose  that  it  is  the 
line  coil  which  is  crossed  with  itself.  In  consequence  of  this  cross 
there  is  less  aggregate  current  flowing  in  that  coil  around  the 
relay  core  than  througli  the  rheostat  coil.  It  will  thus  follow  that 
the  strength  of  current  flowing  through  the  line  coil  must  be  in- 
creased in  order  to  enable  us  to  balance  the  relay  lever.  To  produce 
this  result  we  shall  find  that  we  will  have  to  largely  increase  the  re- 
sistance in  the  rheostat  to  divert  a  greater  portion  of  the  current  to 
the  line ;  but,  of  course,  a  quadruplex  will  not  work  well  on  a  bal- 
ance obtained  in  this  way. 

When  an  abnormal  balance,  such  as  the  above,  is  obtained,  it  is 
a  good  plan  to  ask  the  distant  station  how  many  ohms  resistance  he 
obtains  a  balance  with.  If  his  balance  is  normal  you  may  suspect 
either  of  your  relays,  and  examine  them,  although  it  does  not  follow 
always  that  the  trouble  is  there. 

It  is  presumed  that  every  person  in  charge  of  a  circuit  knows  the 
normal  resistance  of  the  wire  under  his  charge.  Therefore,  if  the 
balance  should  give  about  twice  the  usual  resistance,  it  is  likely  that 
the  ground  coil  at  the  distant  end  has  become  detached,  and  in  con- 
sequence you  are  not  only  balancing  against  the  line  but  also  his 
rheostat,  through  which  you  are  getting  your  "ground."  This 
trouble  is  comparatively  easy  of  detection. 

When  it  happens  that  B  does  not  get  any  battery  from  you  on  a 
certain  .  quadruplex,  and  has  informed  you  to  that  effect,  via 
another  wire  perhaps,  it  is  best,  first  to  ascertain  whether  your 
battery  reaches  the  switch,  testing  for  it  in  both  positions  of  your 
pole  changer  and  transmitter.  If  it  does  not,  then  the  fault  is,  of 


84  THE  QUADRUPLEX. 

course,  located  between  the  switch  and  the  quadruplex  battery. 
Next  test  for  the  battery  at  the  screw-post  of  the  polar  relay  from 
which  the  wire  runs  to  the  switch  ;  next  at  the  screw-post  of  the 
same  instrument  where  the  line  wire  enters  the  relay  ;  next  at  the 
screw-post  of  the  No.  2  relay  whence  the  line  wire  makes  its  exit, 
and  afterwards  at  the  screw-post  at  which  the  line  wire  enters 
that  instrument.  Suppose  that  at  this  latter  post  you  feel  battery, 
but  do  not  at  the  exit  screw-post,  in  such  an  event  it  locates  the 
fault  between  these  two  points.  It  is  probably  a  broken  wire  under 
the  base  board  of  the  instrument,  one  of  the  fine  wires.  But, 
wherever  the  trouble  may  be,  it  is  most  quickly  and  certainly  found 
by  this  point-to-point  test.  A  correct  diagram  of  the  connections  is, 
therefore,  very  essential  to  enable  those  who  cannot  carry  the  con- 
nections in  mind  to  follow  out  the  route  of  the  wires. 

It  should  be  borne  in  mind  that  if  the  trouble  is  occasioned  by 
the  current  having  found  a  short  route  to  the  ground,  as  sometimes 
happens,  it  will  be  almost  impossible  to  locate  the  trouble  with  the 
fingers,  as  the  metallic  route  to  the  ground  offers  so  little  resist- 
ance to  the  current,  in  comparison  with  that  offered  by  the  body, 
that  not  enough  current  will  pass  by  the  body  to  make  itself  felt. 

When  "  deep  seated "  trouble  has  overtaken  a  quadruplex  cir- 
cuit, and  it  is  uncertain  at  which  end  of  the  wire  the  trouble  is  (the 
wire  having,  of  course,  been  changed  for  one  known  to  be  reliable, 
so  that  the  fault  cannot  be  laid  to  it),  and  each  station  claiming 
that  the  fault  or  "  bug "  (as  a  fault  on  multiplex  systems  is  now 
generally  technically  termed),  is  at  the  other  end,  the  best  plan,  by 
all  odds,  is  to  ask  the  distant,  station  to  test  your  quadruplex  set 
against  another  set  in  his  office,  if  he  has  more  than  one  set.  If 
not,  test  your  set  against  a  set  known  to  be  free  from  trouble  in 
some  other  station.  Should  the  same  trouble  still  appear  in  your 
set,  that,  of  course,  proves  conclusively  that  the  trouble  is  in  your 
set.  If  your  set  now  works  O.  K.,  however,  it  as  certainly  shows 
that  the  seat  of  the  fault  is  in  the  distant  quadruplex,  and  the 
manager  thereof  should  be  informed  of  the  result  of  said  test ; 
whereupon,  it  is  to  be  supposed  that  he  will  set  about  with  renewed 


THE  QUADRUPLEX.  85 

vigor  to  locate  the  fault,  and  generally  with  better  success.  You 
need  not  be  surprised,  however,  after  the  trouble  has  disappeared, 
should  the  distant  station  calmly  ask  you,  notwithstanding  the  cir- 
cumstances, "What  did  you  find?  "  The  importance  of  keeping  all 
the  locals  connected  with  a  quadruplex  set  in  first-class  condition, 
and  all  the  local  contact  points  well  cleaned,  cannot  be  mentioned 
too  often.  The  locals  should  not  be  allowed  to  run  down  until 
they  actually  fail,  before  renewal,  nor  should  the  local  contact 
points  be  permitted  to  remain  unfiled  until  they  actually  stick. 

It  has  frequently  happened  that  quadruplex  sets  have  been  ren- 
dered virtually  useless  for  days  at  a  time,  the  trouble  being  attrib- 
uted to  main  line  or  main  battery  faults,  instead  of  which  it  has 
been  an  unheeded  weak  local  or  faulty  local  contact  point. 

It  would  be  impossible  to  enumerate  all  the  different  sources  of 
trouble  which  are  likely  to  arise  on  a  quadruplex  system.  Those 
that  I  have  alluded  to  are  among  the  most  frequent. 

It  would  undoubtedly  add  much  to  the  successful  handling  of 
the  quadruplex  if  every  one  connected  with  it  would  frankly  state 
the  cause  of  trouble,  when  he  has  found  it,  to  the  operator  or  per- 
son in  charge  at  the  other  end.  The  latter  has  seen  the  symptoms 
occasioned  by  the  trouble.  If  he  were  at  once  notified  as  to  the 
exact  nature  of  the  fault,  he  would  be  able  at  once  to  direct  the  dis- 
tant station  to  the  seat  of  trouble,  when  next  the  same  symptoms 
should  manifest  themselves,  and  thus  time  would  be  saved.  Instead 
of  so  doing,  however,  it  has  become  almost  a  rule  for  every  man- 
ager to  hide  any  trouble  happening  in  his  own  set,  and  merely  to 
say  that  probably  a  loose  wire  "  shook  out,"  or  something  equally 
vague.  This  pernicious  custom  is  probably  due  to  the  fact  that  some 
superintendents  require  so  many  explanations  as  to  the  reason  why 
such  and  such  trouble  was  not  obviated,  or  not  discovered  sooner, 
that  a  manager  rarely  allows  a  fault  to  be  definitely  located  in  his 
office  more  than  once.  It  is  thus,  perhaps,  an  open  question  whether 
it  is  really  to  the  benefit  of  the  service  that  managers,  who,  as  a 
rule,  are  not  apt  to  willfully  allow  trouble  to  occur,  or  to  sit  idly 
by  when  it  has  occurred,  should  be  held  so  strictly  to  task. 


TELEGRAPH    REPEATERS. 

BY    WM.    MAVEK,    JR. 

After  Columbus  had  shown  the  wise  men  of  Spain  how  an  egg 
could  be  made  to  stand  on  end,  they  doubtless  conceded  that  it 
was  a  very  simple  feat,  although  they  had  previously  spent  some 
time  and  thought  in  the  attempt  to  solve  it ;  and  it  is  likely  that 
had  any  one  ventured  on  a  second  explanation  of  the  mystery,  the 
wise  men  would  have  considered  it  quite  unnecessary. 

In  like  manner  it  is  possible  that  to  those  who,  by  study  or 
explanation,  have  familiarized  themselves  with  the  principle  and 
operation  of  the  standard  repeaters,  an  article  on  that  subject  at 
this  late  date  may  appear  superfluous ;  but  to  such  as  have  not 
been  shown  how  the  egg  may  be  made  to  stand  on  end,  so  to  speak, 
the  subject  is  as  obtuse  as  it  ever  was. 

It  is  very  questionable  whether,  on  an  average,  one  out  of  ten 
operators  throughout  the  country  is  familiar  with  the  principle  or 
mode  of  operation  of  any  of  the  repeaters  now  in  use.  Indeed,  the 
writer  has  been  told  by  several  of  his  friends  that  they  have  found 
the  action  of  repeaters  as  difficult  to  comprehend  as  that  of  the 
quadruplex. 

This  is,  no  doubt,  an  exaggerated  statement,  but  it  is  nevertheless 
true  that  to  many  the  manner  in  which  the  repeater  performs  its 
functions  is  a  mystery. 

This  condition  of  affairs  is  probably  due  in  many  cases  to  a  total 
lack  of  interest  in  the  matter.  Again,  it  may  be  owing  to  a  habit 
which  some  inventors  or  draughtsmen  have  of  displaying  their 
diagrams  to  the  very  worst  advantage,  with  regard  to  clearness,  so 
that  to  a  novice  it  becomes  an  almost  insurmountable  task  to  follow 
out  the  labyrinth  of  lines,  crossed  in  some  places  so  carelessly  that 
it  is  difficult  to  determine  whether  a  joint  is  not  meant ;  and  in 


REPEATERS.  87 

other  places  so  poorly  jointed  that  it  becomes  a  question  whether 
the  lines  are  not  meant  to  cross  each  other  there.  In  other  diagrams 
the  student  traces  a  wire  until  it  is  brought  up  to  the  screw  post  of 
a  certain  instrument,  and  there  it  stops  short.  He  sees  that  several 
other  wires  lead  out  of  that  instrument  by  other  screw  posts,  but 
which  of  those  is  the  one  he  wishes  to  trace  is  a  discouraging 
conundrum. 

These,  at  least,  are  some  of  the  difficulties  which  met  the  writer 
in  his  search  after  knowledge  on  this  and  like  subjects,  and,  con- 
sequently, in  the  following  descriptions  he  will  strive  to  avoid  fall- 
ing into  similar  errors. 

In  the  days  of  stage  coaching,  as  we  are  all  aware,  a  pair,  or  may- 
be two  pairs,  of  horses  would  be  detailed  to  draw  the  coach  to  a 
certain  station,  having  reached  which  point  they  were  relieved  by  a 
fresh  set  of  horses  termed  a  relay.  The  stage  was  then  drawn  by 
these  horses  to  the  next  relay  station,  when  another  change  of 
horses  would  be  made,  and  so  on. 

The  obvious  reason  for  these  changes  or  relays  was  that  the 
horses  had  become  fatigued,  and  although  they  might  have  gone 
farther,  the  work  would  not  have  been  done  so  quickly  or  so  well 
as  by  the  fresh  set  of  horses. 

Now,  what  the  relay  of  horses  did  for  the  stage  coach,  repeaters 
practically  do  for  the  telegraph  message.  They  take  it  off  the 
hands  of  a  tired  wire,  if  such  an  expression  may  be  used,  and  pass 
it  on  with  fresh  vigor  to  another  wire. 

It  is  a  question  whether  the  name  "  repeater,"  as  applied  to  the 
repeater  of  to-day,  is  not  a  misnomer,  or  at  least  somewhat  inappro- 
priate. The  instrument  which  we  know  as  a  "  relay  "  is,  perhaps, 
more  correctly  a  repeater.  It  repeats  to  the  sounder  what  is  pass- 
ing on  the  main  line.  The  instruments  composing  an  automatic 
repeater  do  relay  the  message  from  one  wire  to  another,  which  is 
exactly  what  the  relay  did  when  its  present  name  was  given  to  it 
by  Morse,  as  will  be  shown  later. 

Repeaters  are  rendered  necessary  on  telegraph  wires,  because  it 
is  impossible  to  insulate  a  wire  so  perfectly  that  a  portion  of  the 


88  REPEATERS. 

electricity  on  the  wire  will  not  escape  at  each  point  of  insulation. 
Hence  a  certain  amount  of  electricity  passes  to  the  ground  at  every 
pole  along  a  line,  and  consequently  the  longer  a  line  may  be,  the 
more  electricity  will  escape  to  the  earth  in  this  manner,  so  that  on 
long  lines  (or  even  on  short  lines  in  wet  weather,  for  then  each 
insulator  becomes  comparatively  a  better  conductor,  and  so  permits 
more  current  to  escape,)  the  current  that  reaches  the  distant  end 
becomes  quite  feeble.  But,  even  if  the  question  of  imperfect  insu- 
lation were  set  aside,  the  operation  of  Ohm's  well-known  law  of 
electricity,  viz.,  that  the  strength  of  current  on  a  line  is  equal  to 
the  electro-motive  force  divided  by  the  resistance  of  the  wire,  would 
confine  the  successful  working  of  a  circuit  within  certain  limits. 
Therefore  it  is  found  advantageous  on  circuits  over  a  certain  length 
to  insert  midway,  or  at  stated  intervals,"  sets  of  repeaters,  with  fresh 
batteries,  etc.  The  intervals  at  which  repeaters  are  placed  of  course 
depend  to  a  great  extent  on  the  conducting  capacity  of  the  wire  used. 

Professor  Morse  at  first  had  an  idea  that  the  best  effects  could  be 
obtained  from  an  electro-magnet  (designed  for  telegraphic  pur- 
poses) by  winding  it  with  wire  of  the  same  size  and  material  as  that 
used  on  the  line.  The  consequences  were  that  the  instruments 
were  not  only  very  unwieldy,  but  very  poor  magnets.  It  is  easy 
to  imagine  that  such  was  the  case  when  it  is  stated  that  the  first 
pair  of  magnets  made  for  Professor  Morse  weighed,  including  attach- 
ments, three  hundred  pounds  each.  Mr.  Charles  T.  Smith,  now 
employed  by  the  Western  Union  Telegraph  Company  in  New  York 
city,  who  was  connected  with  the  Morse  telegraph  system  in  its 
earliest  days,  and  to  whom  I  am  partly  indebted  for  this  interest- 
ing information,  subsequently  made  two  electro-magnets  coiled  with 
a  somewhat  smaller  gauge  of  wire  than  those  just  mentioned.  The 
coils  of  Mr.  Smith's  magnets  were  first  covered  with  gum  shellac, 
and  afterwards  with  a  coating  of  thick  glue.  They  only  weighed 
seventy-five  pounds  each. 

Professor  Morse  very  early  in  his  experiments  discovered  that  he 
could  not  generate  sufficient  magnetism  to  operate  his  electro-mag- 
nets at  a  greater  distance  than  from  fifteen  to  twenty  miles,  the 


REPEATERS.  89 

cause  of  which,  as  we  know  now,  and  as  Morse  afterward  learned, 
was  that  his  electro-magnets  were  wound  with  such  coarse  wire 
that  there  were  comparatively  few  convolutions  around  the  core  of 
the  magnet,  and  as  the  strength  of  an  electro-magnet  increases  with 
the  number  of  convolutions  of  wire  around  the  core  as  well  as  with 
the  strength  of  current  flowing  through  the  coils,  the  resultant  mag- 
netism in  the  professor's  first  instruments  was  very  feeble.  The 
idea  struck  him,  however,  that  while  he  could  not  satisfactorily 
operate  his  magnet  on  a  line  of  any  great  length,  yet  he  might  cause 
a  magnet  operated  at  a  limited  distance  to  transmit  into  another 
wire  of  the  same  length,  and  then  cause  that  second  wire  to  repeat 
into  a  third  wire,  and  so,  as  he  thought  and  said,  in  this  way  en- 
circle the  globe  with  a  wire. 

Fig.  41  shows  the  manner  in  which  the  professor  proposed  to  pro- 
long his  circuit.  It  is  seen  that  line  A  relays  into  line  B  by  means 
of  the  armature  of  R',  and  B  into  C  by  the  aid  of  R",  and  so  on. 
But  by  this  arrangement  it  will  be  observed  that  there  is  no  way 
of  sending  messages  back  from  D  to  A.  To  overcome  this,  Mr. 
Morse  used  another  wire,  as  seen  in  Fig.  42,  giving  Rf  in  that  fig- 
ure control  of  line  B,  etc.  The  electro-magnets  which  performed 
that  service  Mr.  Morse  properly  termed  relays,  and  that  name  all 
line  electro-magnets  have  since  retained,  so  that  when  automatic 
relaying  instruments  were  invented,  the  word  repeater  was  probably 
applied  to  them  as  a  distinguishing  name.  A  working  model  of  this 
method  was  publicly  shown  in  the  University  of  New  York,  but 
it  never  went  into  practical  operation.  Mr.  Morse,  however, 
adapted  this  invention  to  the  work  of  operating  the  secondary  or 
local  circuit,  and  the  manner  of  operating  the  relays  was  maintained 
a  profound  secret  for  a  long  time,  the  magnet  and  its  connections 
being  enclosed  in  a  locked  box. 

THE  BUTTON  REPEATEE. 

In  1846,  the  Woods  button  repeater  was  introduced;  but  in  the 
meantime,  by  the  use  of  improved  electro-magnets,  the  distance  at 
which  relays  could  be  practically  worked  had  much  increased. 


90 


REPEATERS. 


REPEATERS.  91 

Fig.  43  is  a  diagram  of  an  improved  form  of  button  repeater  now 
in  use. 

Before  describing  its  action  let  us  first  investigate  the  necessity 
for  such  an  instrument,  and  for  this  purpose  the  reader  will  please 
consider  that  for  the  present  the  dotted  lines  D  D  D'  D',  and  the 
button  switch  B  R  are  out  of  the  circuit. 

By  examining  the  diagram  it  will  be  seen  that  line  No.  1  runs 
through  relay  R'  and  is  led  through  the  armature  of  the  repeating 
sounder  R  S'  to  the  battery  B'  and  ground ;  and  that  line  No.  2 
goes  through  R"  and  through  the,  armature  of  R  S  to  its  battery  B 
and  ground.  By  this  arrangement  R',  having  control  of  R  S  by 
means  of  the  local  circuit,  should,  it  would  seem,  be  able  to  open  and 
close  No.  2  circuit  at  the  point  x  at  pleasure,  and  in  like  manner 
R",  having  control  of  R  S',  should  be  able  to  close  and  open 
No.  1  circuit.  But  it  is  not  so,  for  let  us  suppose  that  an  operator 
on  No.  1  circuit  opens  his  key ;  this  allows  the  armature  of  R'  to 
fall  back,  which  in  turn  opens  R  S,  and  its  armature,  being  drawn 
up  by  the  retractile  spring,  opens  the  No.  2  circuit  at  x.  This 
action  opens  relay  R",  which  in  turn  opens  R  S',  and  the  latter 
breaks  the  circuit  of  No.  2  line.  This  is  all  right  so  far,  appar- 
ently, for  we  have  both  circuits  open,  but  the  operator  on  No.  1  line 
now  wishes  to  close  his  circuit,  and  consequently  closes  his  key, 
but  that  does  not  close  his  circuit,  as  it  is  still  open  at  R  S',  and 
thus  No.  1  circuit  remains  open,  precisely  as  if  an  operator  at  a 
receiving  station  had  his  key  open,  and  in  that  case  No.  2  circuit  is 
also  kept  open ;  hence  a  deadlock  must  ensue.  This  was  probably 
the  reason  why  Morse  suggested  the  use  of  two  wires  for  his  system 
of  relaying.  At  all  events  it  is  a  sufficient  reason. 

Now,  to  describe  in  what  manner  the  button  repeater  overcomes 
this  trouble,  let  us  consider  that  the  dotted  lines  D  D  D'  D'  and 
the  button  switch  B  R  are  now  in  the  circuit.  "We  will  assume 
that  No.  2  line  wishes  to  send  into  No.  1. 

For  this  purpose  the  operator  attending  the  button  repeater  at 
the  repeating  station  A  turns  the  button  to  the  left  as  shown  in  the 
figure,  so  that  a  strip  of  metal  indicated  by  the  short  black  lines  on 


92 


REPEATERS. 


REPEATERS.  93 

the  handle  of  the  button  switch  joins  the  metal  points  1  and  2 
together.  This  gives  line  No.  2  two  routes  to  battery  B  and 
ground,  one  via  the  dotted  lines  D  D,  and  the  other  via  the  arma- 
ture of  R  S.  Again  assume  that  No.  2  opens  his  key ;  the 
armature  of  R"  falls  back  and  opens  the  local  circuit  of  R  S', 
which  breaks  line  No.  1  at  x',  and  this  again  opens  R',  which  of 
course  opens  R  S  and  breaks  line  No.  2  at  a;, 'but  the  route  via  D 
D  remains  intact,  so  that  No.  2  can  close  his  own  circuit  when 
next  he  closes  his  key,  which  in  turn  closes  R",  which  closes  the 
local  circuit  of  R  S',  and  this  again  closes  N6.  1  circuit.  Thus,  as 
long  as  the  button  switch  is  held  in  that  position,  No.  2  can  repeat 
into  No.  1.  Should  No.  1  wish  to  break  No.  2,  the  attending  opera- 
tor at  A  turns  the  button  so  that  it  will  cover  contact  points  3  and 
4,  which  gives  No.  1  the  same  control  over  No.  2  as  the  latter  pre- 
viously had  over  the  former. 

One  advantage  that  this  form  of  button  repeater  has  over  some 
others  is,  that  when  the  handle  is  directly  in  the  center,  each  line 
may  be  worked  from  station  A  as  independent  circuits. 

Button  repeaters  are  also  useful  when  it  is  necessary  to  send 
copies  of  the  same  press  reports  over  two  different  circuits  from  a 
central  circuit,  J.,  for  instance,  in  the  diagram.  When  used  for 
this  purpose  a  key  is  inserted  in  either  No.  1  or  No.  2  circuit  at  A, 
and  thus  the  operator  at  A,  by  moving  the  handle  to  the  proper 
side,  can  transmit  into  both  circuits. 

AUTOMATIC  REPEATERS. 

In  the  description  of  the  button  repeater,  Fig.  43,  it  was  shown  that 
it  was  necessary  to  keep  the  circuit  of  the  sending  office  intact  at 
the  repeating  station,  at  the  same  time  that  the  said  sending  office 
was  enabled  to  repeat  into  another  circuit  by  having  control  of  a 
repeating  sounder,  through  the  armature  of  which  the  wire  of  the 
circuit  to  be  repeated  into  was  led.  We  saw  in  the  explanation  of  the 
button  repeater  that  this  object  was  accomplished  by  means  of  the 
metal  strip  on  the  handle  of  the  button  switch,  and  the  dotted-line 
circuit,  which  insured  a  continuous  circuit  to  the  sending  office. 


94  REPEATERS. 

This  plan  for  repeating,  however,  while  quite  successful,  had  a 
bad  feature,  inasmuch  as  it  required  the  constant  presence  of  an 
operator  at  the  button  repeater  to  watch  for  breaks  and  to  turn  the 
handle  at  the  right  moment.  It  will  therefore  be  readily  surmised 
that  an  instrument,  or  a  combination  of  instruments,  which  would 
dispense  with  the  services  of  this  operator,  by  automatically  pre- 
serving intact  the  circuit  of  the  sending  station,  at  the  same  time 
allowing  each  station  to  break  the  other  when  desired,  was  much 
sought  after. 

Mr.  Charles  S.  Bulkleyhas  the  credit  of  having  invented  the  first 
automatic  repeater.  It  was  called  an  open  circuit  repeater,  but  as 
it  has  been  obsolete  for  years  I  shall  not  describe  its  action  here. 

Mr.  Bulkley  imitated  Professor  Morse  in  the  manner  of  keeping 
his  invention  a  profound  secret  from  curious  investigators,  by  fitting 
up  a  labyrinth  of  wire  coils  around  his  instruments.  But  it  was 
not  long  before  other  styles  of  automatic  repeaters  were  invented 
by  Farmer,  Woodman,  Hicks,  Haskins,  Milliken,  Catlin,  Toye,  and 
a  host  of  others,  the  majority  of  which  repeaters,  although  quite 
efficient,  never  came  into  general  use.  Of  these  the  Milliken,  which 
was  adopted  as  the  standard  automatic  repeater  of  the  Western 
Union  Company,  and  the  Toye  repeater,  which  is  quite  extensively 
employed  in  Canada,  are  about  the  only  repeaters  now  in  general 
use.  For  this  reason  I  shall  limit  the  descriptions  of  the  various 
repeaters  to  these  two,  more  especially  as  they  are  widely  different 
in  their  methods  of  performing  a  similar  function. 

Fig.  44  is  a  diagram  of  the  connections  of  the  Milliken  repeater. 

In  the  figure,  the  western,  or  No.  1  circuit  is  led  to  the  tongue 
of  transmitter  Tl  and  thence,  when  that  transmitter  is  closed,  to  the 
battery  Bl.  The  eastern  circuit  is  led  to  transmitter  Tl  and 
through  battery  -B,  also  to  the  ground.  It  is  seen  that  the  arma- 
ture of  relay  Rl  controls  the  transmitter  Tl  by  a  local  circuit  shown 
by  dotted  lines,  and  that  the  armature  of  relay  It?  in  like  manner 
controls  transmitter  Tl.  Relay  Rl  thus  can  repeat  into  the  eastern 
circuit  at  will,  for  at  each  motion  of  transmitter  T[  the  eastern 
circuit  is  made  or  broken  at  the  point  X1.  In  the  same  way  relay 


REPEATERS. 


95 


96  REPEATERS. 

R2  can  repeat  into  the  western  circuit  by  operating  the  transmitter 
T\  as  it  opens  or  closes  the  western  circuit  at  the  point  X. 

We  see  that  there  are  also  two  other  local  circuits  in  the  diagram, 
one  from  the  extra  relay  RXZ  to  the  bar  of  transmitter  T\  and 
completed  through  the  insulated  screw  /S"  ;  and  the  other,  from 
relay  R X1  to  the  bar  of  T-,  completed  through  the  insulated  screw 
S.  These  extra  relays  are  supported  in  the  position  shown  in  the 
figure  by  brass  standards.  It  is  the  function  of  each  of  these  extra 
relays  RX1  and  RX*  to  keep  the  armature  of  the  adjoining  line 
relay  closed  while  its  circuit  is  being  repeated  into.  They  do  so 
in  the  following  manner :  Let  us  assume  that  the  east  opens  his 
key.  This  allows  the  armature  of  Rl  to  fall  back,  which  action 
opens  the  local  circuit  of  T'*,  thus  permitting  that  instrument  to 
open,  in  doing  which  it  removes  battery  Bl  from  the  western  circuit, 
and  opens  that  circuit.  This  of  course  demagnetizes  the  relay  M\ 
and  if  unrestrained  its  armature  would  also  fall  back  and  open  the 
local  circuit  of  Tl,  which  in  turn  would  break  the  eastern  circuit 
at  the  point  JT1,  and  give  us  the  exact  conditions  which  were  de- 
scribed in  the  early  part  of  the  description  of  Fig.  43.  But  the 
armature  of  R l  is  not  allowed  to  fall  back,  for  at  the  moment  that 
the  transmitter  T2  was  allowed  to  open,  that  instant  the  local  cir- 
cuit of  RX1  was  broken  at  S,  and  this  allowed  the  armature  of 
RX{  to  fall  back  against  the  armature  of  R\  and  as  the  retractile- 
spring  of  RX1  is  purposely  made  stronger  than  that  of  the  relay  R1, 
it  keeps  the  armature  of  R1  firmly  against  its  local  contact  point, 
and  thus  transmitter  Tl  is  kept  closed,  and  by  this  means  the  route 
of  the  eastern  circuit  through  Tl  is  preserved  intact,  as  the  diagram 
shows,  at  the  repeating  station,  so  that  when  the  east  again  wishes 
to  close  the  western  circuit  he  closes  his  own  key,  which  by  clos- 
ing the  eastern  circuit  attracts  the  armature  of  R2,  which  by  clos- 
ing T2  closes  the  western  circuit,  and  also  the  local  circuit  of  RX1, 
thereby  also  withdrawing  its  armature  from  the  armature  of  R1. 
But  as  now  the  western  circuit  is  closed,  there  is  no  tendency  on 
the  part  of  the  latter  armature  to  fall  back.  When  the  west  wishes 
to  repeat  into  the  east,  the  above  described  action  is  simply  reversed. 


REPEATERS.  97 

Supposing  that  the  east  now  has  his  key  open  with  the  result 
shown  in  the  diagram,  when  the  west  wishes  to  break  he  will  open 
his  key.  This  does  not  yet  change  the  position  of  the  instruments 
at  the  repeating  station,  as  the  western  circuit  is  still  open  at  Jf, 
transmitter  T'2 ;  when,  however,  the  east  next  closes  his  key,  in  so 
doing  he,  of  course,  allows  the  relay  72 2  to  magnetize.  This 
attracts  its  armature,  which,  by  closing  the  local  circuit,  closes  the 
transmitter  T72,  and  the  western  circuit  is  now  closed  at  JT,  and  the 
local  circuit  of  RX1  is  closed  at  S.  This  action  withdraws  the 
armature  of  RX1  from  the  armature  of  relay  R  \  and^the  key  of 
the  western  operator  being  open  for  the  purpose  of  breaking,  the 
western  circuit  still  remains  open.  Therefore  the  armature  of  R l 
falls  back,  opening  the  local  circuit  of  Tl,  and  breaking  the  eastern 
circuit  at  X1.  The  eastern  operator,  now  finding  his  circuit  open, 
keeps  his  key  closed,  and  thus  the  west  is  permitted  to  make  any 
necessary  remarks  by  causing  relay  R l  to  operate  the  transmitter 
571,  which,  as  we  have  seen,  breaks  or  closes  the  eastern  circuit  at 
X1  at  each  motion. 

In  practice  the  transmitters  are  furnished  with  buttons,  not 
shown  in  the  diagram,  by  means  of  which  the  automatic  repeating 
portions  are  cut  off,  thus  allowing  each  of  the  circuits  to  be  worked 
as  a  single  wire  from  the  repeating  station. 

I  have  said  that  the  local  circuits  of  RX1  and  RX2  are  broken 
at  the  instant  that  the  respective  main  circuits  are  broken  at  X  and 
X1.  In  reality  the  local  circuits  at  R X1  and  RX-  are  broken  an 
instant  before  the  main  circuits,  for  the  moment  that  the  levers  of 
the  transmitters  begin  to  move,  that  moment  the  local  circuits  of 
RX l  and  RX-  are  broken,  whereas  the  tongues  of  Tl  and  T*  fol- 
low the  contact  screws  until  prevented  by  the  bent  arms  AA\  and 
by  this  arrangement  the  holding  fast  at  the  proper  time  of  the  arma- 
tures of  R l  and  R'1  by  the  armature  of  RX*  and  R X1  is  insured. 

In  the  transmitters  used  in  the  Milliken  repeater,  the  bent  arms 
are  insulated  from  the  tongues,  and  the  bar  from  the  screws  H  and 
H\  so  that  any  possil  lity  of  interference  between  the  local  and 
line  batteries  of  RX1  a.vd  RX2  is  removed.  From  this  description 


98  REPEATERS. 

it  will  be  observed  that  the  action  is  in  a  measure  mechanical,  the 
armatures  of  the  extra  relays  RX1,  and  RX2  holding  the  armatures 
of  the  line  relays  as  firmly  and  promptly  against  their  contact  points 
at  the  proper  moment,  as  would  be  possible  for  the  finger  of  an 
operator  to  do  ;  indeed,  incomparably  more  promptly  and  firmly. 

The  Milliken  repeater  was  used  for  a  long  time  between  Jackson- 
ville, Fla.,  and  Havana,  on  the  Cuba  cable,  the  repeating  stations 
being  at  Punta  Rassa,  Fla.,  and  Key  West,  a  total  distance  of  560 
miles,  320  of  which  is  through  a  cable.  The  Milliken  has,  however, 
recently  been  supplanted  on  this  route  by  the  Johnston  repeater. 

THE  TOYE  REPEATER. 

As  I  have  said,  the  operation  of  the  Toye  repeater  is  entirely 
different  from  the  Milliken.  It  is  considered  much  simpler.  It 
certainly  possesses  an  advantage  over  the  Milliken,  inasmuch  as 
the  instruments  used  in  its  operation  are  ordinary  line  relays  and 
continuity-preserving  transmitters,  and  need  but  two  local  bat- 
teries. The  Milliken  repeater  requires  four  local  batteries  in  its 
operation.  The  Milliken,  however,  has  the  reputation  of  being  the 
most  generally  efficient  of  repeaters. 

Fig.  45  shows  the  connections  of  the  Toye  repeater.  The  main 
circuits  are  first  led  from  the  line  through  the  posts  of  the  trans- 
mitters, thence  to  the  tongues  of  those  instruments,  to  the  line 
relays,  the  batteries  and  ground.  The  bar  of  each  transmitter  is 
connected  with  a  rheostat,  the  object  of  which  will  shortly  be 
explained. 

I  will  assume  that  the  west  wishes  to  repeat  into  the  eastern 
line.  He  has  opened  his  key,  which  opens  Rl  and  permits  its 
armature  to  fall  back,  opening  the  local  circuit  of  T,  and  breaking 
the  eastern  circuit,  as  seen  in  the  figure  at  the  point  -X"1. 

Just  prior  to  the  moment,  however,  that  the  eastern  circuit  was 
broken  at  X1,  the  battery  B  was  shunted,  via  the  bar  or  lever  of 
Tinto  the  rheostat  H,  as  shown  in  the  diagram.  Thus  the  relay 
R  has  not  lost  its  magnetism,  and  its  armature  is  still  retained 
against  its  contact  point,  thereby  keeping  the  transmitter  Tl  sta- 


REPEA  TERS. 


100  REPEATERS. 

tionary,  and  consequently  the  circuit  of  the  sending  office  is  kept 
unbroken  at  the  repeating  station,  which,  as  we  have  already  seen, 
is  the  desideratum  in  all  automatic  repeaters.  This  action  is  also 
reversed  when  the  east  wishes  to  send  to  the  western  circuit. 

The  resistance  of  the  rheostats  is  adjusted  to  correspond  with  the 
resistance  of  the  line  circuits,  so  that  the  batteries  meet  with  a 
similar  resistance  in  either  position  of  the  transmitters. 

This  description  makes  it  plain  that  it  would  be  difficult  to  con- 
struct a  more  simple  repeater  than  the  Toye.  It,  however,  has  two 
slight  drawbacks,  one  of  which  is,  that  as  it  depends  on  the  pres- 
ence of  the  main  batteries  to  keep  the  relays  magnetized  at  the 
proper  time,  it  can  only  be  employed  at  the  terminals  of  lines,  where 
such  batteries  are.  The  other  drawback  consists  of  the  fact  that 
the  batteries  are  kept  constantly  closed. 

COMBINATION  DUPLEX  AND  SINGLE  CIRCUIT  REPEATERS. 

The  introduction  of  the  Stearns  Duplex,  and  subsequently  the 
quadruplex  systems  of  telegraphy,  dispensed  with  the  services  of 
many  sets  of  automatic  repeaters. 

These  multiplex  sj^stems  did  not  render  the  wires  capable  of 
being  worked  at  any  greater  distance  than  heretofore,  but  it 'was 
found  a  very  easy  matter  to  cause  one  duplex  or  quadruplex  set  to 
repeat  into  another  quadruplex  or  duplex  set,  without  the  use  of 
any  of  the  regular  automatic  repeaters. 

The  manner  in  which  this  repetition  is  effected  is  very  simple ; 
but,  as  it  may  not  be  generally  known,  I  shall  herewith  describe  it. 

Let  us  take,  for  example,the  cable  quadruplex  circuit  between  New 
York  and  Sydney,  C.  B.,with  the  quadruplex  repeaters  at  Bangor,  Me. 

At  the  repeating  station,  Bangor,  there  are  two  quadruplex  sets. 
One  of  these  works  direct  with  New  York,  the  other  with  Sydney. 

I  can,  I  think,  simplify  the  description  if  the  reader  will  take  a 
piece  of  blank  paper  and  roughly  draw  on  the  left-hand  side  of  the 
paper  a  neutral  relay  and  a  transmitter,  and  immediately  benei  th 
these  instruments,  a  polar  relay  and  i\  pole  changtr,  ani  call  this  t,  e 
New  York  set. 


REPEATERS.  101 

On  the  opposite  side  of  the  paper  draw,  in  the  same  way,  another 
neutral  relay  and  transmitter,  a  polar  relay  and  pole  changer,  and 
call  this  the  Sydney  set. 

Now  draw  lines  representing  a  local  circuit  from  the  contact 
points  of  the  neutral  relay  of  the  New  York  set  to  the  magnet  of  the 
pole  changer  of  the  Sydney  set,  and  insert  a  local  battery.  This 
gives  the  neutral  relay  control  of  the  pole  changer. 

In  the  same  manner  give  the  neutral  relay  of  the  Sydney  set  con- 
trol of  the  pole  changer  of  the  New  York  set. 

Draw  lines  again  from  the  polar  relay  of  the  New  York  set  to  the 
transmitter  of  the  Sydney  set,  and  in  like  manner  connect  the  arma- 
ture of  the  polar  relay  of  the  Sydney  set  with  the  transmitter  of  the 
New  York  set. 

It  is  now  seen  that  when  the  neutral  relay  of  the  New  York  set  is 
operated,  its  armature  operates  the  pole  changer  of  the  Sydney  set, 
and  when  the  neutral  relay  of  the  latter  set  is  worked,  it  operates  the 
pole  changer  of  the  New  York  set ;  that  the  polar  relay  of  the  New 
York  set  operates  the  transmitter  of  the  Sydney  set,  and  the  polar  re- 
lay of  the  latter  in  turn  operates  the  transmitter  of  the  New  York  set. 

In  other  words,  the  armatures  of  the  different  relays  act  simply 
as  keys  to  operate  the  various  pole  changers^and  transmitters  of  the 
opposite  sets. 

I  think  it  will  now  be  quite  plain  to  the  reader  that  when,  for 
instance,  the  operator  in  the  New  York  office,  who  may  be  sending 
on  the  second  side,  manipulates  his  transmitter,  his  signals  will 
operate  the  neutral  relay  of  the  New  York  set  in  Bangor,  which  in 
turn,  by  operating  the  pole  changer  of  the  Sydney  set  in  Bangor, 
repeats  the  signals  on  to  the  Sydney  office,  and  vice  versa. 

Of  course  a  duplex  set  can  be  caused  to  repeat  into  another 
duplex  set  in  the  same  way. 

It  will  be  noticed  by  the  foregoing  that  the  No.  1  side  of  each 
set  is  made  to  repeat  into  the  No.  2  side  of  the  other  set. 

This  arrangement  is  not  absolutely  necessary,  as  the  first  side  of 
one  set  could  be  just  as  readily  made  to  repeat  into  the  first  side 
of  the  other  set. 


102  REPEATERS. 

The  first-mentioned  arrangement  is,  however,  the  one  generally 
adopted,  probably  to  neutralize  any  atmospheric  condition  which 
would  perhaps  tend,  on  a  long  circuit,  to  make  one  side  work  bet- 
ter than  the  other. 

It  is  quite  frequently  found  that  all  of  a  quadruplex  set  is  not 
required  for  the  handling  of  business  between  certain  points,  and 
that  therefore  half  of  a  set,  that  is  one  side  of  it,  can  be  spared  for 
other  purposes. 

Thus  there  is  a  quadruplex  circuit  between  New  York  and 
Elmira,  one  side  of  which  is  set  apart  for  the  local  business,  while 
the  other  side  is  connected  with  a  single  wire  to  Bradford,  Pa. ;  and 
there  are  many  other  similar  circuits. 

The  utility  of  the  quadruplex  system  is  here  seen,  inasmuch  as 
it  saves  one  wire  for  the  distance  covered  by  the  quadruplex  sys- 
tem— for  instance,  in  the  case  referred  to,  a  wire  between  New 
York  and  Elmira. 

A  combination  circuit  of  a  quadruplex  and  single  circuit  requires 
an  automatic  repeater  at  the  point  where  the  junction  is  made,  and 
several  arrangements  have  been  devised  for  this  purpose,  one  of  the 
first  of  which,  known  as  the  Waterbury  repeater,  I  shall  here 
describe. 

In  Fig.  46,  T  and  N  R  are,  respectively,  the  transmitter  and 
neutral  relay  of  the  second  side  of  a  quadruplex  set,  from  which 
all  but  the  local  connections  have  been  omitted.  R  T  is  a  repeat- 
ing transmitter ;  R  R  is  a  repeating  relay. 

The  single  wire  is  led,  as  may  be  seen  in  the  diagram,  through 
the  repeating  relay  to  the  tongue  of  R  T,  and  thence  to  the  battery 
and  ground. 

There  is  also  an  extra  circuit  shown  by  dotted  lines  from  R  R  to 
the  bar  of  R  T,  in  which  is  inserted  a  local  battery,  also  as  shown. 

When  the  transmitter  72  Tis  open  (as  it  will  be  when  the  neutral 
relay  N  R  is  open),  this  extra  circuit  is  completed  through  R  R, 
and  via  the  bar  and  tongue  of  the  transmitter  at  x',  so  that  when- 
ever R  T  is  open,  the  repeating  relay  will  be  kept  closed. 

It  is,  of  course,  understood  that  the  operator  at  the  distant  end 


REPEATERS. 


103 


TO 


104  REPEATERS. 

of  the  quadruplex,  whom   I  shall  hereafter  call   the  quadruplex 
operator,  can  only  send  or  receive  one  way  at  a  time. 

The  manner  in  which  this  arrangement  acts  is  as  follows :  — 

Suppose  that  the  operator  at  the  distant  end  of  the  single  wire, 
whom  I  shall  refer  to  as  the  Morse  operator,  wishes  to  send  ;  in 
that  case  the  quadruplex  operator  must  keep  his  key  closed,  which 
we  are  all  aware  will  keep  the  neutral  relay  at  the  repeating  station 
closed,  as  seen  in  the  diagram.  Now  when  the  Morse  operator 
opens  his  key  that  action  opens  the  repeating  relay  R  R,  for  it  may 
be  seen  that  the  extra  circuit  is  at  present  open  at  x'.  This  allows 
its  armature  to  fall  back,  opening  the  local  circuit  of  the  quadruplex 
transmitter  jP,  and  thereby  opening  the  neutral  relay  at  the  dis- 
tant end. 

When  the  Morse  operator  again  closes  his  key,  thus  closing  the 
single  wire  circuitj  the  armature  of  R  R  is  attracted,  and  thereby 
again  closes  the  transmitter  T.  Thus  as  often  as  the  Morse  opera- 
tor opens  or  closes  his  circuit,  the  relay  R  R  opens  or  closes  the 
quadruplex  transmitter. 

When  the  quadruplex  operator  wishes  to  send,  he  simply  operates 
his  transmitter,  which  in  turn  opens  or  closes  the  neutral  relay  N 
R  at  the  repeating  station. 

This  action,  by  allowing  the  armature  of  N  R  to  fall  back,  opens 
the  transmitter  R  T,  which  thus  cuts  off  the  single-wire  battery 
from  the  single  wire  at  x',  thus  opening  that  wire.  The  relay  R  R 
does  not,  however,  open  at  this  time,  for,  as  I  have  already  shown, 
the  extra  circuit,  with  its  local  battery,  comes  into  play  the  moment 
that  R  T  opens,  and,  consequently,  the  quadruplex  operator  does 
not  get  his  own  writing  back,  as  he  would  if  R  R  were  not  kept 
closed.  When  the  quadruplex  operator  again  closes  his  transmitter 
the  neutral  relay  N  R  is  again  closed.  This  in  turn  closes  R  T, 
again  connecting  the  single  battery  with  the  single  wire  and  clos- 
ing that  circuit. 

In  this  way  the  quadruplex  operator,  by  controlling  the  neutral 
relay  N  R  at  the  repeating  station,  which,  as  we  have  seen,  con- 
trols the  repeating  transmitter  R  T,  can  operate  the  single  wire  at 


REPEATERS.  105 

will,  for  at  each  motion  of  R  T  the  single  wire's  circuit  is  opened 
or  closed  at  the  point  x'. 

This  arrangement  has  been  found  very  serviceable  in  good 
weather,  but  during  stormy  weather  its  action  is  nqt  so  satisfactory. 
This  is  owing  to  the  fact  that  the  increased  magnetism  in  the  sin- 
gle-wire relays,  in  wet  weather,  necessitates  the  pulling  up  of  the 
relay  spring  to  such  an  extent  that  the  local  battery  of  the  circuit 
becomes  unable  to  hold  the  relay  closed  against  the  increased  ten- 
sion of  the  relay  spring,  and  hence  the  quadruplex  operator  gets  his 
own  writing  back. 

It  may  have  occurred  to  the  reader  that  this  function  could  be 
performed  by  the  use  of  one-half  of  either  of  the  automatic  repeat- 
ers which  I  have  previously  described,  and  such  is  the  case. 

There  are  many  circuits  on  which  one-half  of  the  Milliken  or 
Toye  repeaters  is  used  for  this  purpose  with  entire  success. 

It  is  well  known  that  there  are  a  great  many  quadruplex  sets 
leased  to  broker  firms,  two  firms  generally  being  assigned  to  one 
set,  each  firm  using  one  side  of  a  set. 

In  such  cases  the  quadruplex  sets  are  stationed,  in  the  main 
offices  of  the  company,  while  a  single  wire  known  as  the  "  short  or 
branch  wire"  is  run  direct  from  the  quadruplex  sets  to  the 
brokers'  offices. 

A  repeating  arrangement  is  also  essential  to  the  working  of  this 
plan,  and  a  number  of  different  methods  are  employed,  including  a 
modification  of  the  Toye  and  other  repeaters. 

The  method  employed  in  New  York  city  is  known  as  the  D.  R. 
Downer  repeater — .shown  in  Fig.  47 — a  very  simple  and  effective 
arrangement,  which  I  shall  proceed  to  describe. 

In  the  figure,  ^and  N  R  are  the  transmitter  and  neutral  relay  of 
a  quadruplex  set.  They  may,  however,  be  supposed  to  represent 
equally  well  a  pole  changer  and  polarized  relay.  R  T  is  a  repeat- 
ing transmitter. 

It  is  seen  that  the  neutral  relay  has  control  of  R  T\)j  means  of 
the  local  circuit  shown,  and  that  the  broker's  single  wire  has  con- 
trol of  the  quadruplex  transmitter  T  by  the  route  as  represented  in 


106 


REPEATERS. 


REPEATERS.  107 

the  diagram  through  the  post  of  R  T,  to  the  tongue  of  that  instru- 
ment, thence  to  the  button  switch  S,  through  the  magnet  of  T  to 
the  battery  and  ground.  When  the  broker  at  this  end  (referring 
to  diagram)  wishes  to  send,  it  is  necessary  that  the  broker  at  dis- 
tant end  should  keep  his  key  closed.  This  keeps  N  R  closed,  and 
consequently  also  R  T ;  thus  -tli2  broker  has  unobstructed  control 
of  the  quadruplex  transmitter  T,  for  it  is  evident  that  when  he 
opens  his  key  it  must  open  the  transmitter  T  by  breaking  the  circuit 
of  the  branch  wire  battery.  On  the  contrary,  it  is  quite  as  essen- 
tial that,  when  the  distant  broker  is  sending  to  the  broker  at  this 
end,  the  quadruplex  transmitter  T  at  this  end  should  be  kept  closed, 
and  that  object  is  effected  as  follows : — 

When  the  distant  broker  desires  to  send,  he  opens  his  key ;  this- 
opens  N  R  in  the  diagram,  this  in  turn  opens  R  T,  which  breaks 
the  branch  wire  circuit  at  the  point  Jf,  and  opens  the  sounder  in  the 
broker's  office  at  this  end.  At  the  moment,  however,  that  the 
broker's  wire  is  opened  at  X,  another  extra  circuit,  T  W,  shown  by 
the  dotted  lines,  is  brought  into  play,  namely,  via  the  bar  of  R  Tto 
the  point  X'  in  the  battery,  through  this  small  portion  of  the  battery, 
which  is  known  as  the  "  tap,"  to  the  magnet  of  T  and  back  to  the 
bar  of  R  T  by  way  of  the  tongue  of  that  instrument.  By  this 
means  it  will  be  observed  that  the  quadruplex  transmitter  is  kept 
closed  at  the  right  moment,  without  the  use  of  any  additional  local 
battery.  When  the  distant  broker  again  closes  his  key  or  trans- 
mitter, the  neutral  relay  N  R  is  again  closed,  the  repeating  trans- 
mitter R  T  is  thereby  also  closed,  and  the  battery  is  placed  once 
more  to  the  branch  wire  at  the  point  X,  while  the  tap  wire  is 
disconnected  at  that  point  at  the  same  time. 

It  is  sometimes  necessary  to  cut  off  the  branch  wire  to  facilitate 
the  testing  or  balancing  of  the  quadruplex.  For  this  purpose  the 
switch  S  is  inserted.  By  turning  the  switch  to  the  lower  button  it 
may  be  noticed  that  there  is  a  short  metallic  circuit  formed,  enclos- 
ing the  key  JSTand  controlling  T. 

It  is,  I  suppose,  well  known  that  the  above  described  arrange- 
ment dispenses  with  the  use  of  one  wire  to  the  branch  office. 


108  REPEATERS. 

In  some  cases,  however,  the  repeating  device  is  not  used,  but  in- 
stead two  short  wires  are  furnished,  one  of  which  is  in  direct  connec- 
tion with  the  transmitter,  and  the  other  with  the  neutral  rela}r,  both 
wires  being  grounded  at  the  branch  office. 

In  some  main  offices  one-half  of  the  Toye  repeater  is  also  used  to 
perform  the  necessary  repeating  work  from  the  quadruplex  to  a 
branch  wire. 

By  reference  to  Fig.  47  it  will  be  seen  that  this  can  be  done  very 
easily,  as  follows  :  Remove  the  tap  wire  T  IF  from  the  battery  at  X', 
and  conduct  it  through  a  rheostat  to  the  ground.  No  other  change 
is  necessary.  Of  course  the  resistance  of  the  rheostat  will  require 
to  be  made  equal  to  the  limited  resistance  of  the  branch  wire. 

The  only  advantage  that  I  know  of  in  the  Downer  arrangement 
over  the  Toye,  for  this  purpose,  is  that  mentioned  in  the  description 
of  Che  Toye  repeater,  namely,  that  the  entire  battery  is  not  always 
kept  closed. 

By  the  Downer  plan  the  greater  portion  of  the  battery  is  open 
half  the  working  time. 

I  shall  now  bring  this  chapter  to  a  close  by  giving  one  or  two 
hints  on  the  practical  management  of  repeaters  of  the  latter  class. 

In  the  first  place,  it  should  be  a  rule  to  see  that  the  contact  points 
are  cleaned  regularly,  and  that  the  local  batteries  are  kept  up  to  a 
standard  strength.  It  is  a  good  plan  to  test  the  strength  of  the  local 
batteries  occasionally,  by  withdrawing  the  armature  of  the  instru- 
ments against  the  attractive  force  of  the  magnets.  When  there  is 
a  decided  sign  of  weakening,  the  locals  should  be  at  once  renewed. 

It  is  a  somewhat  common  occurrence  to  find  that  the  writing  on 
the  neutral  relay  is  being  repeated  back  on  the  transmitter. 

This  fact  is  sometimes  brought  to  your  attention  by  the  state- 
ment of  the  distant  end  that  he  is  getting  his  own  writing  back. 

This  effect  may  be  produced  by  one  of  several  causes.  For  in- 
stance, the  branch  office  may  have  his  key  open,  or  the  transmitter 
points  at  X  in  Fig.  47  may  not  be  making  proper  contact,  or  they 
may  need  cleaning.  Your  own  key  may  be  open,  or  the  battery 
mav  have  failed.  To  locate  the  trouble,  first  see  that  the  repeating 


REPEA  TERS.  109 

transmitter  is  acting  properly,  and  that  the  points  are  clean.  File 
them.  Turn  the  button  switch  to  the  left.  If  this  closes  the  trans- 
mitter, it  shows  that  the  local  portion  of  the  battery  is  all  right. 
Next  take  a  piece  of  wire  and  attach  one  end  of  it  to  the  post  of 
the  repeating  transmitter,  the  other  end  to  a  ground.  There  are 
always  plenty  of  good  grounds  around  a  quadruples  set.  If  this 
closes  the  quadruples  transmitter,  it  proves  that  your  battery  is  in 
order,  and  that  the  circuit  is  open  between  you  and  the  branch 
office.  Care  should  be  taken,  however,  to  notice  that  the  trans- 
mitter is  closed  with  somewhat  more  than  the  usual  strength,  be- 
cause it  is  possible  that  the  battery  may  have  partially  run  down, 
and  while  too  weak  to  close  the  transmitter  when  the  full  resist- 
ance of  the  branch  wire  was  in  the  circuit,  is  still  strong  enough  to 
close  the  transmitter  with  the  branch  circuit  cut  off.  These  tests 
can  be  made  within  one  minute  when  one  is  familiar  with  the  mode 
of  proceeding. 

Besides  those  repeaters  which  I  have  described,  and  also  those 
that  I  have  referred  to,  there  have  been  other  forms  of  repeaters 
invented.  For  instance,  repeaters  that  allow  one  wire  to  repeat 
into  two  distinct  circuits,  and  give  each  of  those  two  circuits  the 
power  of  automatically  breaking  the  sending  circuit.  Such  repeat- 
ers have  been  termed  "  three-corner  repeaters." 

Mr.  R.  C.  Edwards,  of  New  York,  has  recently  invented  an 
octuplex  repeater,  which  enables  the  sending  circuit  to  repeat  into 
eight  distinct  circuits,  and  also  allows  each  of  those  circuits  to 
automatically  break  the  sending  circuit. 

There  may  also  be  other  systems  which  have  not  come  under  my 
observation. 

I  have  myself  invented  a  very  simple  multiple  repeater,  by  means 
of  which  one  circuit  can  repeat  into  one,  fifty,  or  a  hundred  or 
more  other  circuits,  each  of  which  other  circuits  can  automatically 
break  the  sending  circuit,  or  it  can  be  arranged  so  that  one  of  a 
system  of,  say  fifty  or  one  hundred  circuits,  can  repeat  into  fifty  or 
one  hundred  circuits  of  another  system,  and  any  one  of  the  latter 
system  can  automatically  repeat  into  all  of  the  former  system. 


WHEATSTOBTE  AUTOMATIC  TELEGRAPH. 

BY    WM.    MAVER,    JR. 

A  general  interest  has  been  created  among  operators  concerning 
the  Wheatstone  automatic  telegraph  since  its  adoption  by  the 
Western  Union  Telegraph  Company  as  its  rapid  telegraph  system. 
A  desire  having  been  evinced  to  learn  more  about  its  manner  of 
working,  I  shall  endeavor  in  this  chapter  to  give  a  detailed  descrip- 
tion of  the  method  of  its  operation. 

It  is,  I  suppose,  generally  known  that  the  Wheatstone  automatic 
system  differs  from  the  American  Rapid  Company's  automatic,  or 
any  other  system  of  fast  automatic  telegraphy  in  this  country  in 
which  the  Morse  alphabet  is  used,  inasmuch  as  it  is  what  may  be 
termed  a  mechanical  automatic  telegraph,  while  the  others  are 
chemical  automatic  systems. 

The  chemical  systems  that  most  resemble  the  Wheatstone  are 
those  that  use  prepared  perforated  paper  for  the  purpose  of  trans- 
mitting signals;  for  instance,  the  American  Rapid  system,  which 
was  fully  described  in  the  columns  of  The  Operator  some  time  ago. 

In  the  latter  system  the  perforated  paper  is  passed  over  a  metal 
cylinder,  which  is  a  continuation  of  the  main  circuit,  and  two 
needles,  or  styles,  connected  with  the  negative  and  positive  ends  of 
batteries  respectively,  are  placed  on  the  top  of  the  paper  in  such  a 
position  that  when  the  punctured  portions  of  the  paper  pass,  the 
needles  are  allowed  to  connect  with  the  cylinder  beneath  the  paper, 
and  thus  permit  a  positive  or  a  negative  current  to  flow  to  the  line, 
according  to  the  situation  of  the  punctures.  This  is  called  direct 
contact. 

At  the  receiving  station  of  this  system  there  is  another  metal  cyl- 
inder (which  is  also  a  part  of  the  main  circuit),  over  which  passes  a 


THE  WHEATS  TONE  AUTOMATIC.  Ill 

ribbon  of  chemically  prepared  paper.  Resting  on  this  paper  is  a 
needle,  likewise  a  part  of  the  circuit.  As  this  paper  is  moistened 
with  a  chemical  preparation,  it  constitutes  a  good  conductor,  and 
when  a  current  of  electricity  is  sent  to  the  wire  from  the  sending  end 
it  passes  through  the  needle  and  the  paper  to  the  cylinder  and 
ground.  While  the  current  is  thus  passing  through  the  paper,  a 
chemical  decomposition  of  the  ingredients  composing  the  solution  in 
which  the  paper  has  been  previously  soaked  takes  place,  and  in  con- 
sequence a  mark,  varying  in  color  according  to  the  constituents  of 
the  solution,  is  recorded  on  the  paper  as  long  as  electricity  is  allowed 
to  flow  through  the  circuit. 

Thus,  by  varying  the  duration  of  the  current  on  the  line,  which 
is  the  function  of  the  perforated  paper,  dots  and  dashes  can  be  sig- 
naled as  required. 

In  the  Wheatstone  system  the  perforated  paper  serves  to  send 
currents  of  either  polarity  to  the  line,  and  also  governs  the  length 
of  the  mark  recorded  at  the  distant  end — but  in  an  entirely  differ- 
ent manner  from  that  just  reviewed. 

Beneath  and  pressing  up  against  the  perforated  paper  in  the 
Wheatstone  system  are  two  needles,  or  small  levers,  the  lower  ends 
of  which  are  connected  by  springs  and  "other  mechanism  to  a 
delicately  constructed  pole  changer. 

When  there  are  no  punctures  in  the  paper  passing  above  the  small 
levers,  the  latter  are  prevented  from  moving  to  their  full  extent, 
and  thus  fail  to  actuate  the  pole  changer.  When  either  of  these 
needles  comes  to  a  hole  in  the  paper  it  passes  through  it  and  makes 
its  full  motion,  and  so  moves  its  connections  that  a  certain  pole  is 
placed  to  the  line. 

At  the  receiving  end  a  polarized  relay  is  placed,  whose  armature 
responds  to  the  changes  of  polarity  at  the  sending  end,  and  operates 
an  inking  apparatus,  which,  when  in  a  certain  position,  records  a 
mark  on  the  receiving  paper. 

This  will  probably  be  sufficient  to  show  the  distinction  between 
a  mechanical  and  chemical  automatic  system.  Each  of  these  re- 
spective systems  has  its  advantages  and  disadvantages,  but  as  it  is 


112 


THE  WHEA  TSTONE  A  UTOMA  TIG. 


not  intended  in  this  chapter  to  discuss  these,  I  shall  merely  mention 
one  or  two  of  the  characteristic  features  of  each. 

In  some  of  the  chemical  methods  there  seems  to  be  almost  no 
limit  to  the  rapidity  with  which  signals  may  be  sent  and  recorded, 
as,  to  a  certain  extent,  it  simply  depends  on  the  frequency  with 
which  the  line  can  be  charged  and  discharged.  This  is  one  of  its 
advantages.  One  of  its  disadvantages  lies  in  the  fact  that  occa- 
sionally the  perforations  in  the  paper  are  not  clearly  punctured,  and 
thus  small  pieces  of  paper  intervene  between  the  direct  contact 
needle  and  the  cylinder,  and  thereby  cause  confusion. 


Fig   48. 

The  speed  at  which  a  mechanical  system  can  be  operated  is  lim- 
ited by  the  rapidity  with  which  the  electro-magnet  can  be  charged 
and  discharged,  and  overcome  the  inertia  of  its  armature,  so  that 
distinct  signals  shall  be  recorded.  One  of  the  advantages  of  the 
latter  system,  and  it  is  a  valuable  one,  is  that  the  receiving  signals 
are  received  on  blue  stiff  paper,  in  clear  Morse  characters.  Another 
is  that  as  the  speed  at  which  signals  arrive  by  this  method  is  not 
beyond  the  rate  at  which  the  receiving  instrument  clerk  can  follow 
them,  any  errors  which  may  occur  are  at  once  detected  and  cor- 
rected. 

It  may,  perhaps,  aid  the  reader  to  an  understanding  of  the  work- 
ing of  the  Wheatstone  system  to  remember  that  the  operation  of 


THE  WHEATSTONE  AUTOMATIC.  113 

the  various  parts  of  its  mechanism  all  tend  to  the  transmission  and 
reception  of  the  Morse  characters.  What  operators  do  by  the  hand 
this  machinery  does  automatically.  We  are  all  aware  that  when  we 
are  sending  on  a  polar  duplex,  or  the  polar  side  of  a  quadruplex 
(the  number  one  side),  to  make  a  dot  we  have  to  cause  the  key  to 
make  two  motions,  one  down  and  one  up.  In  doing  so  we  have 
changed  the  polarity  of  the  current  twice.  By  closing  the  key, 
which  is,  of  course,  equivalent  to  closing  the  pole  changer,  we  send 
a  current  to  line,  which  attracts  the  armature  of  the  distant  polar- 
ized relay  to  the  local  contact  point.  By  opening  the  key  again, 
we  place  a  different  pole  to  the  line,  and  it  repels  the  armature  from 
the  local  contact  point.  To  make  a  dash  we  simply  allow  our  fin- 


Fig.  49. 

gers  to  linger  an  instant  longer  on  the  key  when  it  is  closed.  To 
make  the  space  we  keep  the  key  open  a  moment.  What  we  thus 
do  by  the  guidance  of  our  faculties,  the  automatic  is  required  to  do 
by  the  arrangement  of  its  component  parts.  By  recollecting  what 
is  required  of  the  mechanism,  we  may  be  the  better  able  to  compre- 
hend the  manner  in  which  it  accomplishes  this  purpose,  when  it 
is  explained. 

Let  us  suppose  that  when  we  close  the  key  on  the  polar  duplex 
or  quadruplex,  we  send  a  positive  current  to  the  line,  and  that  the 
polarized  relay  is  so  arranged  that  it  is  the  positive  current  that 
attracts  the  armature  of  the  relay  to  the  local  contact  point,  and 


114 


THE  WHEATSTONE  AUTOMATIC. 


that  when  we  open  the  key  we  place  a  negative  pole  to  the  line, 
which  repels  the  armature  from  the  local  points. 

Now,  if  we  attach  a  pen  to  the  armature  and  cause  a  strip  of 
paper  to  pass  in  close  proximity  to  it,  if  the  key  is  closed  we  shall 
have  a  mark  on  the  paper  until  we  again  open  the  key.  This  is 
similar  to  what  occurs  in  the  Wheatstone  system  by  the  combined 
operation  of  the  perforated  paper,  which  acts  the  part  of  the  opera- 
tor's fingers,  inasmuch  as  it  controls  the  levers  under  the  paper,  and 
the  transmitting  mechanism.  These  levers  correspond  to  the  Morse 
key,  as  they  actuate  the  pole  changer,  which  latter  in  turn  oper- 
ates the  distant  polarized  relay  with  its  inking  attachment,  as  will 
be  explained  in  the  detailed  description  of  the  Wheatstone  trans- 
mitter and  receiver. 


Fig.  50. 

The  Wheatstone  automatic  apparatus  consists  of  three  parts, 
namely :  the  perforator,  the  transmitter,  arid  the  receiver. 

The  perforator  is  the  instrument  by  means  of  which  the  message 
is  prepared  for  transmission,  and  is  shown  in  full  in  Fig.  48.  It 
consists  of  three  distinct  boxes,  the  largest  of  which  supports  the 
stand  D,  pn  which  messages  intended  for  preparation  are  placed 
for  the  convenience  of  the  punching  operator.  It  also  contains  the 
paper  to  be  punched.  The  smallest  box  F  contains  the  punching 
apparatus  proper.  Box  Cr  serves  to  support  the  latter  box,  and  to 
receive  the  residue  of  the  perforations  which  rapidly  accumulate. 
The  paper  which  is  seen  issuing  from  the  largest  box  is  of  a  stiff 
white  pattern,  and  has  been  previously  prepared  for  punching  by 
having  been  dipped  in  olive  oil,  so  as  to  dispense  as  much  as  possi- 
ble with  the  paper  dust,  which,  unless  the  paper  is  so  prepared,  is 
found  to  cause  trouble  by  clogging  up  the  punching  apparatus. 
The  oil  also  serves  to  lubricate  the  machinery  of  the  perforator. 


THE  WHEATSTONE  AUTOMATIC.  115 

Figure  49  is  a  top  view  of  box  F,  Fig.  48.  The  buttons  or  discs 
A  B  and  C  are  mechanically  connected  to  three  levers  or  keys  be- 
neath the  cover  of  the  box,  and  these  levers  are  again  respectively 
connected  in  such  a  manner  to  three,  one,  and  four  sharp,  hollow 
cylinders,  that  when  either  of  the  discs  Ay  B  or  C  is  depressed,  the 
corresponding  sharp  cylinder  is  urged  forward  through  the  paper 
ribbon,  cutting  clear  round  holes  therein. 

Fig.  50  shows  these  hollow  cylinders  as  arranged. 

The  depression  of  disc  A  causes  three  of  these  cylinders  to  punch 
the  paper  in  one  vertical  line  (see  Fig.  51),  which  corresponds  to  a 
dot ;  B  causes  one  only  to  punch  (Fig.  52),  which  is  the  spacing 
mark ;  C  causes  four  of  them  to  perforate  the  paper  (see  Fig.  53), 
which  correspond  to  the  dash.  There  is  another  and  important  piece 
of  mechanism  in  this  box,  not  shown  in  the  diagram.  It  consists  of 
a  small  star  wheel,  the  teeth  of  which  fit  closely  into  the  central  or 


Fig.  51.  Fig.  52.  Fig.  53. 

space  holes.  The  same  action  that  impels  any  of  the  punching 
cylinders  forward  jerks  the  star  wheel  around,  and  it  is  thus  made 
the  medium  for  carrying  the  paper  along  as  it  is  perforated.  The 
punching  operator  is  provided  with  two  small  iron  mallets  tipped 
with  rubber,  by  means  of  which  he  depresses  the  discs. '  In  practice 
the  dot  and  dash  discs  have  a  dot  and  dash  engraved  on  them,  but, 
of  course,  this  is  not  necessary  to  distinguish  them  after  a  few 
hours  practice.  The  dot  disc  is  on  the  left  side,  the  dash  disc  on 
the  right  side,  and  the  space  disc  is  in  the  middle.  To  make  the 
letter  (7,  for  instance,  the  dot  disc  is  struck  twice  in  succession,  then 
the  space  disc,  and  again  the  dot.  The  spacing  disc  is  struck  twice 
between  words,  and  once  between  each  letter.  This  method  of 
punching  entails  a  considerable  amount  of  manual  labor,  and  soon 
becomes  very  tedious.  The  most  expert  punchers  do  not  maintain 
a  speed  of  more  than  thirty-five  words  per  minute  for  any  length  of 


116 


THE  WHEATSTONE  AUTOMATIC. 


time.  As  it  would  be  impracticable  to  make 
a  dash  long  enough  for  the  American  Morse 
signal  for  the  letter  L,  it  has  been  given  the 
characters  of  two  dots  and  two  dashes. 

•  j^  Fig.  54  shows  the  words  The  Operator  pre- 

•  pared  for  transmission  in  the  manner  above  de- 
scribed. 

i  ^ 

,  The  Wheatstone  transmitter,  Fig.  55,  is  con- 

tained in  a  brass  box  about  eight  inches  long, 

I  **          five  inches  high,  and  three  wide. 

.  Fig.  56  is  an  exterior  view  of  the  box,  show- 

ing the  transmitting  apparatus  proper. 

The  paper   is  represented  by   the    straight 

i  ^          line  P,  and  moves  in  the  direction  indicated 

t  by  the  arrow. 

T# 

,  ^    *         The  levers  S  and  M  are  kept  in  their  up- 
£     right  positions  by  the  retractile -springs  shown. 
1  These  levers  are  so  adjusted  by  the  screw  posts 

|    ^,         F  and  F',  that  the  lever  M  is  allowed  to  go 
slightly  farther  to  the  right  than  the  lever  S. 
1  This  apparently    trifling  arrangement  should 

•  be  remembered,  as  it  will  be  seen  farther  on 
that  it  serves  a  useful  purpose. 

R  is  a  beam  of  ebonite  or  other  insulating 
1  material,  supported  by  a  pivot  in  its  center, 

»  ^}           running  backward  into  the  box.     This  pivot 
is  connected  with  the  clock-work  contained  in 
j  &s  the  box,  in  such  a  manner  that  when  the  clock- 

work is  in  operation  it  imparts  to  the  beam 
a  rocking  motion,  similar  to  the  Avalking  beam 
of  a  steamboat.  An  upward  tendency  is  given 
to  the  levers  S  and  M  by  the  springs  S  and  S' 
attachpd  to  the  crank  levers  A  and  B,  but  the  extent  of  the  up- 
ward motion  of  the  levers  $and  Mis  regulated  by  the  metal  pins  1 
and  2  inserted  in  the  beam,  and  also  by  the  prepared  paper  P. 


THE  WHEATSTONE  A  ITTOMA  TIC. 


117 


118 


THE  WHEATSTONE  AUTOMATIC 


Attached  to  the  crank  levers  A  and  B  are  the  straight  levers  H 
and  H'.  The  ends  of  these  pass  through  the  projecting  pieces  P 
and  P',  which  are  fixed  to  the  movable  disc  D.  H  and  H1  are 
provided  with  small  collars  or  collets  K  and  K,  which  prevent  their 
ends  from  going  beyond  a  certain  distance  through  the  projections 
P  and  P1. 

The  disc  D  is  pivoted  to  the  frame-work  of  the  box,  and  is 
divided  by  an  insulating  material  into  two  parts,  one  of  which  is 
connected  to  the  ground,  and  the  other  to  the  line.  Metal  pins  are 
also  inserted  in  this  disc,  and  on  one  or  other  of  these  pins,  accord- 
ing to  the  position  of  the  disc  D,  the  crank  levers  C  and  Z  are  made 


Fig.  56. 

to  rest  by  the  action  of  the  retractile  springs  E  and  E'.  In  the  present 
instance  the  beam  R  has  moved  upward,  thus  permitting  the  lever 
M  to  ascend  under  the  influence  of  spring  S'.  The  lever  H'  has 
thus  pushed  the  disc  D  over  to  its  present  position.  The  same 
motion  of  the  beam  has,  by  aid  of  the  pin  1,  pushed  the  lever  S 
down,  and  this  motion  of  lever  S  has  withdrawn  the  lever  H  from 
P',  so  that  the  lever  H'  was  unopposed  in  pushing  over  disc  D. 
The  small  roller  E,  being  pivoted  on  a  tension  spring,  aids  the 
motion  of  the  disc  in  this  wise :  when  the  piece  P,  going  either 
way,  passes  the  center  of  the  roller  E,  the  latter  gives  the  disc  D  a 
jerk  over.  In  Fig.  56  the  lever  M  has  passed  through  a  hole  in 
the  paper,  and  thus  has  made  its  full  motion  with  the  above  effect. 
It  may  also  be  seen  that  this  position  of  disc  D  places  a  positive 


THE  WHEATSTONE  AUTOMATIC.  119 

pole  to  the  line.  If,  now,  the  beam  make  another  motion  whereby 
the  lever  S  is  permitted  to  ascend,  and  the  lever  M  is  made  to  de- 
scend, it  may  be  seen  that  the  collet  of  lever  H  will  be  driven 
against  the  piece  P',  and  as  the  collet  of  the  lever  H'  is  now  with- 
drawn from  P,  the  position  of  the  disc  D  is  changed,  and  the  nega- 
tive pole  sent  to  the  line,  as  shown  in  Fig.  57.  Thus  we  can  see, 
presuming  there  is  no  paper  passing  above  to  limit  the  motion  of 
the  levers  M  and  S,  that  as  often  as  the  beam  is  moved  up  and 
down,  the  polarity  of  the  battery  is  changed. 


Fig.  57. 

Directly  under  the  paper  P,  in  Fig.  56,  is  a  small  star  wheel,  not 
shown  in  the  diagram.  This  wheel  is  geared  with  the  clock-work 
also,  and  in  such  a  way  that  when  the  beam  R  makes  one  motion, 
the  star  wheel  moves  around  the  space  of  one  tooth.  The  teeth  of 
this  star  wheel,  as  in  the  punching  apparatus,  fit  into  the  central 
holes  of  the  prepared  paper,  and  as  it  revolves  carry  the  paper 
forward. 

Let  us  now  follow  the  operation  performed  by  this  apparatus  in 
making  the  letter  R,  as  seen  in  Fig.  58,  namely,  two  vertical  holes, 
a  blank,  and  a  series  of  two  sets  of  two  vertical  holes.  As  the  right 
hand  end  of  beam  R  moves  upward,  the  lever  M  passes  up  through 
the  topmost  hole  in  the  paper,  as  it  appears  in  Fig.  58,  or  the 
hrtle  nearest  the  frame  of  the  box.  This,  as  I  have  already  said, 
i-ends  a  marking  current  to  the  line,  to  which  the  armature  at 


120  THE  WHEATSTONE  AUTOMATIC. 

distant  end  responds.  The  right  end  of  the  beam  moves  down- 
ward ;  the  left  end  moves  upward,  and  with  it  the  lever  S.  At  the 
same  time  the  star  wheel  moves  the  paper  forward  one  space,  and 
this  movement  of  the  paper  brings  the  lowest  of  the  two  vertical 
holes  now  opposite  the  lever  S  (for  it  will  be  remembered  that  the 
lever  S  is  adjusted  a  little  to  the  left  of  J/),  which  passes  through 
that  hole.  Thus  the  polarity  is  again  changed,  and  the  inker  is  with- 
drawn from  the  paper  at  the  distant  end.  The  beam  makes  another 
motion,  and  the  star  wheel  carries  the  paper  one  tooth  forward  ;  but 
it  is  seen  that  the  lever  M  meets  with  no  hole,  and  its  upward 
course  is,  therefore,  blocked  by  the  paper,  and  the  pin  2  moves  up 
unfollowed  by  M  ;  as  the  lever  M  consequently  has  not  made  its 
full  motion,  the  lever  H'  has  not  pushed  the  disc  D  over,  and  thus 
the  same  pole  is  continued  to  the  line,  and  a  blank  space  is  left  on 
the  receiving  paper.  Another  motion  of  the  beam  brings  the  lever 
S  up7  to  the  paper,  but  it,  too,  in  the  same  way,  is  prevented  from 
making  its  full  phase,  and  the  disc  D  remains  as  it  was,  which  fur- 
ther increases  the  space  on  receiving  paper.  A  further  motion  of 
the  beam  now  brings  the  lever  M  again  up  to  the  paper,  and  also 
opposite  the  topmost  hole  of  the  second  series  of  holes,  which  the 
star  wheel  has  advanced.  The  lever  thus  makes  a  full  movement, 
and  this  sends  a  marking  current  once  more  to  the  line.  Again 
lever  S  is  brought  up  to  the  paper,  and,  also  finding  a  hole,  passes 
through  it,  again  changing  the  polarity,  and  the  marker  is  withdrawn  ; 


R.  A. 

Fig.  58.  Fig.  59 

thus  another  dot  is  recorded.  The  polarity  is  again  changed  twice 
as  before,  and  another  dot  is  marked,  which  now  gives  us  on  the 
receiving  paper  a  dot,  a  space,  and  two  dots. 

The  diagonal  position  of  the  dash  perforations  simply  reverses  the 
action  necessary  for  a  spacing  current.     Take,  for  instance,  the  let- 


THE  WHEATSTONE  A  UTOMATIC. 


121 


ter  A,  Fig.  59.  The  upper  hole  allows  a  marking  current  to  be 
sent.  Immediately  the  lower  hole  reverses  it,  and  a  dot  is  recorded. 
The  second  upper  hole  sends  another  marking  current  to  line,  and, 
as  owing  to  the  position  of  the  next  lower  hole  the  beam  will  fe- 
quire  to  make  two  motions  before  the  lever  S  reaches  it,  the  mark- 
ing current  continues  to  the  line,  and  a  dash  is  allowed  to  be  re- 
corded on  the  receiving  paper. 

Of  course  these  actions  take  place  very  rapidly,  so  much  so  that 
when  the  apparatus  is  at  full  speed,  namely,  about  250  words  per 
minute,  it  is  impossible  to  follow  the  motion  of  the  levers.  This 
statement  may  be  better  understood  when  it  is  reflected  that  at 
this  rate  of  speed  the  levers  move  about  4,000  times  per  minute. 


Fig.  60. 

THE  WHEATSTONE  RECEIVER. 

The  receiving  instrument  is  contained  in  n.  brnss  box  of  about 
the  same  dimensions  as  the  transmitter.  See  Fig.  60.  Within  the 
box  are  the  polarized  relay,  previously  mentioned,  and  the  clock- 
work, hereafter  referred  to,  which  is  operated  by  a  spring. 

Thf3  receiving  paper  passes  over  a  roller  which  is  in  close  proxim- 


122 


THE  WHEATSTONE  AUTOMATIC. 


ity  to  the  inking  apparatus.  The  roller  is  actuated  by  the  clock-work, 
and  is  the  means  by  which  the  receiving  paper  is  carried  along. 

The  instrument  is  supplied  with  a  governor,  which  regulates  the 
speed  of  the  clock-work. 

Fig.  61  is  a  diagram  of  a  part  of  the  interior  of  the  receiver. 

P  is  a  permanent  magnet,  in  the  ends  or  poles  of  which  semi- 
circular notches  are  made,  into  which  the  armatures  of  the  polar- 
ized relay  M  are  loosely  fitted.  A  is  an  axis  to  which  these 


Fig.  61. 

armatures  are  fixed.  It  extends  above  and  below  the  electro-mag- 
nets. At  its  lower  end  connections  are  arranged  for  the  operation 
of  a  local  sounder  S,  which  is  used  when  the  circuit  is  switched 
from  the  automatic  to  manual  working.  The  upper  extension  of 
the  axis  A  is  bent  in  the  manner  shown.  The  poles  of  the  electro- 
magnets M  are  placed  opposite  each  other.  One  of  the  upper  poles 
of  M  is  omitted  in  the  diagram  to  show  the  position  of  the  arma- 
tures between  the  poles.  The  armatures  oscillate  between  these 
poles  in  response  to  the  changes  of  polarity  at  the  distant  end.  As 
the  extension  E  is  also  attached  firmly  to  the  axis  A,  it  is  evident 
that  its  motion-must  correspond  to  that  of  the  armatures.  When 


THE  WHEA  TS  TONE  A  UTOMA  TIC.  123 

there  is  no  current  on  the  line,  and  when  the  armatures  are  prop- 
erly adjusted,  they  remain  on  whichever  side  last  placed,  in  the 
same  manner  as  the  armature  of  the  quadruplex  polarized  relay. 

His  the  axle  of  a  cog  wheel  which  is  geared  with  the  clock- 
work. To  the  right  end  of  this  axle,  which  protrudes  through  the 
frame  work  of  the  box,  is  attached  a  small  wheel  IF,  which  rotates 
opposite  the  center  of  the  roller,  over  which  the  paper  is  seen  pass- 
ing in  Fig.  56.  This  small  wheel  also  rotates  within,  but  does  not 
touch  the  groove  of  another  wheel  F,  which  revolves  in  an  ink  well/. 
In  this  groove  sufficient  ink  is  brought  up  by  capillary  attraction  to 
the  wheel  W  to  keep  its  edge  supplied  without  friction. 

The  axle  X  is  given  a  slight  tension  toward  the  up-curled  end  of 
the  extension  E.  There  is  a  small  notch  in  this  up-turned  end 
through  which  the  axle  X  passes.  This  slight  support  is  all  that 
the  axle  receives  in  addition  to  that  from  its  cog  wheel. 

When  a  negative  or  spacing  current  is  placed  to  the  line  the  ex- 
tension E,  moving,  as  I  have  said,  in  unison  with  the  armatures, 
holds  back  the  axle  X,  and,  consequently,  the  wheel  IF,  from  the 
receiving  paper.  When  a  positive  or  marking  current  is  sent  to 
the  line,  the  extension  E  is  withdrawn  from  the  axle  X,  and  thus 
the  wheel  IF  is  allowed  to  touch  and  mark  the  paper. 

The  polarized  relay  being  practically  inaccessible  within  the  box, 
the  armature  is  adjusted  by  means  of  apparatus  placed  outside  of 
the  box. 

The  play  of  the  armatures,  and  likewise  the  marking  wheel,  is 
very  limited,  being  about  ^  of  an  inch.  This  is  necessarily  so,  on 
account  of  the  rapid  motions  made  when  the  apparatus  is  working 
at  full  speed.  For  the  same  reason  all  of  the  above  mechanism  is 
of  very  light  construction,  more  so  than  the  diagram  would,  per- 
haps, indicate.  It  may  be  further  stated,  as  showing  the  need  of 
delicate  apparatus  for  fast  working,  that  the  sounder  S  in  the  local 
circuit,  which  is  adjusted  as  ordinarily,  ceases  to  record  intelligibly 
after  the  speed  exceeds  say  125  words  per  minute,  which  is  owing 
chiefly  to  the  fact  that  its  armature  is  unable  to  travel  the  distance 
to  which  it  is  adjusted,  in  the  now  diminished  time. 


124 


THE  WHEATSTONE  AUTOMATIC. 


THE  WHEATSTONE  AUTOMATIC.  125 

The  Wheatstoue  automatic  system  may  be  worked  on  a  single  or 
duplex  wire.  The  foregoing  description  of  the  transmitter  and 
receiver  applies  to  the  actions  that  take  place  when  it  is  worked  as  a 
duplex.  On  the  Western  Union  lines  it  is  operated  almost  en- 
tirely on  the  duplex  system.  By  this  method  the  capacity  of  a  wire 
is  increased  to  about  500  words  per  minute. 

Fig.  62  shows  the  connections  necessary  for  working  the  Wheat- 
stone  duplex,  and  also  the  connections  required  to  change  the  sys- 
tem from  the  automatic  pole  changer  to  the  Morse  pole  changer. 
This  change  becomes  necessary  when  it  is  desired  to  hold  con- 
versation or  to  balance  the  wire,  and  is  made  by  means  of  the  triple 
switch  (F)  contained  within  the  transmitter.  In  the  diagram  the 
switch  is  arranged  for  the  automatic  system.  One  motion  of  the 
lever  controlling  the  switch  transfers  it  to  the  Morse.  The  connec- 
tions may  be  readily  traced  by  any  one  familiar  with  the  duplex 
system.  The  circuit  is  as  follows  :  From  the  earth  at  E  E  to  the 
disc  D,  to  lever  Z,  to  right-hand  button  of  switch  to  negative 
pole  of  battery,  to  left-hand  button  of  switch  and  lever  (7,  to  disc  D 
and  central  button  of  switch,  thence  to  the  receiver,  where  the  cir- 
cuit divides,  one  portion  going  through  the  galvanometor  Cr  to  line, 
and  the  other  through  the  galvanometer  to  rheostat  and  ground. 

As  the  polarized  relay  is  inaccessible,  owing  to  its  position  in  the 
receiver,  the  manner  of  obtaining  a  balance  of  the  wire  is  different 
from  that  on  the  quadruples.  The  distant  station  is  requested  to 
open  or  close  his  key.  This  presents  a  certain  pole  to  line  and  gives 
the  home  galvanometer  needle  a  certain  deflection.  The  polarity  of 
the  home  battery  is  now  reversed,  and  if  a  different  deflection  is 
thereby  caused,  it  is  an  evidence  that  the  lume  station  is  out  of 
balance,  and  the  rheostat  is  adjusted  until  the  galvanometer  needle 
remains  stationary  under  the  changes  of  home  polarity,  when  the 
balance  is  correct. 

Fig.  63  shows  the  Wheatstone  connections,  as  arranged  for  work- 
ing the  system  on  single  wires.  In  this  arrangement  it  will  be  seen 
that  the  circuit  is  from  the  earth  to  the  galvanometer,  thence  to 
the  middle  button  of  the  triple  switch.  Here  the  current  has  two 


126 


THE  WHEA  TSTONE  A  UTOMA  TIC. 


routes ;  one  is  to  the  pin  1  on  the  rocking  beam  R,  thence  to  the 
crank  lever  A,  thence  to  pin  2  on  rocking  beam,  thence  to  disc  D, 
to  the  battery,  to  the  right-hand  button  on  switch,  thence  to 
lever  Z  and  disc  I),  and  to  the  line.  The  other  route  is  from  the 
middle  button  of  switch  to  an  interposed  resistance  R,  thence  to 
the  disc  Z>,  etc.,  as  before.  This  interposed  resistance  is  generally 
very  high,  so  that  when  the  route  via  the  rocking  beam  is  intact, 
only  a  very  small  portion  of  the  current  will  go  through  the  resist- 
ance, hence  the  full  strength  of  current  virtually  goes  to  line.  But 
when  it  happens,  for  instance,  that  the  lever  J/is  prevented,  by  rea- 
son of  there  being  no  hole  in  the  prepared  paper,  from  following  pin 


It);    '—  4. I— Ht±= 

j^J-xfe).-      ;- .1...,-.,  '  I  I i  i  T]     7 


Fig.  63. 


2  in  the  beam  R  in  its  upward  motion,  the  circuit  is  broken  at  that 
point,  and  the  current  is  compelled  to  go  through  the  resistance  R, 
and  the  strength  of  the  current  is  thereby  greatly  diminished ;  but, 
as  we  have  seen  that  when  either  of  the  levers  S  or  M"does  not 
make  its  full  motion,  the  polarity  of  the  current  is  not  changed,  and 
as  we  also  know  that  the  tendency  of  the  armature  of  the  receiving 
relay  is  to  stay  where  last  placed,  this  diminished  current  will  be 


THE  WHEATSTONE  AUTOMATIC.  127 

quite  sufficient  to  keep  the  armature  in  its  present  position  until 
the  polarity  of  the  current  is  again  changed. 

When  the  Wheatstone  was  first  invented  this  resistance  was  not 
used,  the  wire  being  allowed  to  remain  open  while  either  of  the 
levers  M  or  S  was  detached  from  its  respective  pin  1  or  2,  but  it 
was  found  that  greater  speed  could  be  attained  by  introducing 
the  above  resistance,  as  the  wire  is  thus  kept  at  the  same  potential 
until  the  next  actual  reversal  of  polarity. 

The  key  shown  in  Fig.  63  is  a  double  current  or  pole  changing 

key.     It  is  still  used  on  the  Wheatstone  system  in  England,  but 

has  been  displaced  here  by  the  ordinary  pole  changer,  as  shown  in 

.  Fig.  62,  it  having  been  found  that  firmer  contacts  could  be  made  by 

the  latter  method. 

In  Figs.  62  and  63  the  transmitter  switch  is  placed  for  automatic 
sending. 

The  punching  instruments  in  the  Wheatstone  department  at 
195  Broadway,  by  means  of  which  messages  are  prepared  for  auto- 
matic transmission,  have  recently  been  supplied  with  pneumatic 
pressure.  Heretofore  the  operation  of  punching  the  paper  has  been 
quite  arduous,  as  considerable  force  is  required  to  perforate  the 
paper  with  the  precision  which  is  essential.  The  old  punching  in- 
strument, with  its  three  discs,  is  still  retained,  but  it  is  now  placed 
within  a  tight-fitting  iron  frame.  A  small  portion  of  the  upper  part 
of  this  frame  is  boxed  in,  and  the  air  pressure  is  allowed  to  enter 
the  box  at  one  of  the  sides.  Three  cylindrical  pistons  protrude 
from  the  bottom  of  the  box,  and  these  pistons  are  placed  directly 
over  the  discs  of  the  ordinary  punching  instrument.  The  iron 
frame-work  is  also  furnished  with  three  keys,  representing  the  three 
discs  of  the  punching  apparatus,  and  these  keys  control,  by  means 
of  a  stiff  wire,  three  valves  within  the  inclosed  box.  A  slight  de- 
pression of  one  of  these  keys  thus  opens  its  corresponding  valve  and 
allows  the  air  to  rush  in,  which  forces  the  desired  piston  down  with 
a  quick,  strong  motion  upon  the  disc  beneath  it,  causing  it  to  perfo- 
rate the  paper.  The  air  pressure  at  present  employed  is  six  and 
one  half  pounds  to  the  square  inch. 


128  THE  WHEATSTONE  AUTOMATIC. 

Messages  intended  for  transmission  by  the  Wheatstone  system 
are  first  handed  to  the  perforators  or  punchers  for  preparation. 
The  prepared  paper  is  then  placed  on  the  transmitter  by  the  clerk 
in  charge  of  that  instrument.  Another  clerk  is  in  charge  of  the 
receiving  instrument.  As  the  messages  are  received  on  the  receiv- 
ing paper  they  are  given  to  transcribing  clerks,  who  translate  the 
Morse  characters  into  writing.  These  clerks  are  termed  "  writers." 

Thus,  by  the  automatic  system,  each  message  in  the  course  of 
transmission  and  reception  passes  through  the  hands  of  four  clerks, 
as  against  two  by  the  Morse  system. 

The  Wheatstone  automatic  telegraph  is  the  standard  automatic 
system  of  the  British  Postal  Telegraph,  and  it  is  in  extensive  opera- 
tion in  that  country.  It  is  found  very  useful  there,  especially  for 
press  reports,  on  account  of  the  fact  that  many  similar  special  dis- 
patches are  sent  to  several  different  cities,  and,  as  when  the  paper 
is  once  prepared,  it  may  be  used  any  number  of  times,  much  work 
is  thus  dispensed  with.  The  automatic  system  is  also  found  very 
serviceable  in  case  of  prostration  of  the  wires,  owing  to  storms  or 
from  any  other  cause,  as  in  the  meantime  the  business  may  be  pre- 
pared for  automatic  transmission,  and  as  soon  as  one  or  two  wires, 
are  obtained,  may  be  quickly  disposed  of. 


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